1 /*
2 * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/g1Allocator.inline.hpp"
32 #include "gc/g1/g1BarrierSet.hpp"
33 #include "gc/g1/g1CollectedHeap.inline.hpp"
34 #include "gc/g1/g1CollectionSet.hpp"
35 #include "gc/g1/g1CollectorPolicy.hpp"
36 #include "gc/g1/g1CollectorState.hpp"
37 #include "gc/g1/g1ConcurrentRefine.hpp"
38 #include "gc/g1/g1ConcurrentRefineThread.hpp"
39 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1FullCollector.hpp"
42 #include "gc/g1/g1GCPhaseTimes.hpp"
43 #include "gc/g1/g1HeapSizingPolicy.hpp"
44 #include "gc/g1/g1HeapTransition.hpp"
45 #include "gc/g1/g1HeapVerifier.hpp"
46 #include "gc/g1/g1HotCardCache.hpp"
47 #include "gc/g1/g1MemoryPool.hpp"
48 #include "gc/g1/g1OopClosures.inline.hpp"
49 #include "gc/g1/g1ParScanThreadState.inline.hpp"
50 #include "gc/g1/g1Policy.hpp"
51 #include "gc/g1/g1RegionToSpaceMapper.hpp"
52 #include "gc/g1/g1RemSet.hpp"
53 #include "gc/g1/g1RootClosures.hpp"
54 #include "gc/g1/g1RootProcessor.hpp"
55 #include "gc/g1/g1StringDedup.hpp"
56 #include "gc/g1/g1ThreadLocalData.hpp"
57 #include "gc/g1/g1YCTypes.hpp"
58 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
59 #include "gc/g1/heapRegion.inline.hpp"
60 #include "gc/g1/heapRegionRemSet.hpp"
61 #include "gc/g1/heapRegionSet.inline.hpp"
62 #include "gc/g1/vm_operations_g1.hpp"
63 #include "gc/shared/adaptiveSizePolicy.hpp"
64 #include "gc/shared/gcHeapSummary.hpp"
65 #include "gc/shared/gcId.hpp"
66 #include "gc/shared/gcLocker.hpp"
67 #include "gc/shared/gcTimer.hpp"
68 #include "gc/shared/gcTrace.hpp"
69 #include "gc/shared/gcTraceTime.inline.hpp"
70 #include "gc/shared/generationSpec.hpp"
71 #include "gc/shared/isGCActiveMark.hpp"
72 #include "gc/shared/preservedMarks.inline.hpp"
73 #include "gc/shared/suspendibleThreadSet.hpp"
74 #include "gc/shared/referenceProcessor.inline.hpp"
75 #include "gc/shared/taskqueue.inline.hpp"
76 #include "gc/shared/weakProcessor.hpp"
77 #include "logging/log.hpp"
78 #include "memory/allocation.hpp"
79 #include "memory/iterator.hpp"
80 #include "memory/resourceArea.hpp"
81 #include "oops/access.inline.hpp"
82 #include "oops/compressedOops.inline.hpp"
83 #include "oops/oop.inline.hpp"
84 #include "prims/resolvedMethodTable.hpp"
85 #include "runtime/atomic.hpp"
86 #include "runtime/flags/flagSetting.hpp"
87 #include "runtime/handles.inline.hpp"
88 #include "runtime/init.hpp"
89 #include "runtime/orderAccess.inline.hpp"
90 #include "runtime/threadSMR.hpp"
91 #include "runtime/vmThread.hpp"
92 #include "utilities/align.hpp"
93 #include "utilities/globalDefinitions.hpp"
94 #include "utilities/stack.inline.hpp"
95
96 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
97
98 // INVARIANTS/NOTES
99 //
100 // All allocation activity covered by the G1CollectedHeap interface is
101 // serialized by acquiring the HeapLock. This happens in mem_allocate
102 // and allocate_new_tlab, which are the "entry" points to the
103 // allocation code from the rest of the JVM. (Note that this does not
104 // apply to TLAB allocation, which is not part of this interface: it
105 // is done by clients of this interface.)
106
107 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
108 private:
109 size_t _num_dirtied;
110 G1CollectedHeap* _g1h;
111 G1CardTable* _g1_ct;
112
113 HeapRegion* region_for_card(jbyte* card_ptr) const {
114 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
115 }
116
117 bool will_become_free(HeapRegion* hr) const {
118 // A region will be freed by free_collection_set if the region is in the
119 // collection set and has not had an evacuation failure.
120 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
121 }
122
123 public:
124 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
125 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
126
127 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
128 HeapRegion* hr = region_for_card(card_ptr);
129
130 // Should only dirty cards in regions that won't be freed.
131 if (!will_become_free(hr)) {
132 *card_ptr = G1CardTable::dirty_card_val();
133 _num_dirtied++;
134 }
135
136 return true;
137 }
138
139 size_t num_dirtied() const { return _num_dirtied; }
140 };
141
142
143 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
144 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
145 }
146
147 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
148 // The from card cache is not the memory that is actually committed. So we cannot
149 // take advantage of the zero_filled parameter.
150 reset_from_card_cache(start_idx, num_regions);
151 }
152
153
154 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
155 MemRegion mr) {
156 return new HeapRegion(hrs_index, bot(), mr);
157 }
158
159 // Private methods.
160
161 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
162 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
163 "the only time we use this to allocate a humongous region is "
164 "when we are allocating a single humongous region");
165
166 HeapRegion* res = _hrm.allocate_free_region(is_old);
167
168 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
169 // Currently, only attempts to allocate GC alloc regions set
170 // do_expand to true. So, we should only reach here during a
171 // safepoint. If this assumption changes we might have to
172 // reconsider the use of _expand_heap_after_alloc_failure.
173 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
174
175 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
176 word_size * HeapWordSize);
177
178 if (expand(word_size * HeapWordSize)) {
179 // Given that expand() succeeded in expanding the heap, and we
180 // always expand the heap by an amount aligned to the heap
181 // region size, the free list should in theory not be empty.
182 // In either case allocate_free_region() will check for NULL.
183 res = _hrm.allocate_free_region(is_old);
184 } else {
185 _expand_heap_after_alloc_failure = false;
186 }
187 }
188 return res;
189 }
190
191 HeapWord*
192 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
193 uint num_regions,
194 size_t word_size) {
195 assert(first != G1_NO_HRM_INDEX, "pre-condition");
196 assert(is_humongous(word_size), "word_size should be humongous");
197 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
198
199 // Index of last region in the series.
200 uint last = first + num_regions - 1;
201
202 // We need to initialize the region(s) we just discovered. This is
203 // a bit tricky given that it can happen concurrently with
204 // refinement threads refining cards on these regions and
205 // potentially wanting to refine the BOT as they are scanning
206 // those cards (this can happen shortly after a cleanup; see CR
207 // 6991377). So we have to set up the region(s) carefully and in
208 // a specific order.
209
210 // The word size sum of all the regions we will allocate.
211 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
212 assert(word_size <= word_size_sum, "sanity");
213
214 // This will be the "starts humongous" region.
215 HeapRegion* first_hr = region_at(first);
216 // The header of the new object will be placed at the bottom of
217 // the first region.
218 HeapWord* new_obj = first_hr->bottom();
219 // This will be the new top of the new object.
220 HeapWord* obj_top = new_obj + word_size;
221
222 // First, we need to zero the header of the space that we will be
223 // allocating. When we update top further down, some refinement
224 // threads might try to scan the region. By zeroing the header we
225 // ensure that any thread that will try to scan the region will
226 // come across the zero klass word and bail out.
227 //
228 // NOTE: It would not have been correct to have used
229 // CollectedHeap::fill_with_object() and make the space look like
230 // an int array. The thread that is doing the allocation will
231 // later update the object header to a potentially different array
232 // type and, for a very short period of time, the klass and length
233 // fields will be inconsistent. This could cause a refinement
234 // thread to calculate the object size incorrectly.
235 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
236
237 // Next, pad out the unused tail of the last region with filler
238 // objects, for improved usage accounting.
239 // How many words we use for filler objects.
240 size_t word_fill_size = word_size_sum - word_size;
241
242 // How many words memory we "waste" which cannot hold a filler object.
243 size_t words_not_fillable = 0;
244
245 if (word_fill_size >= min_fill_size()) {
246 fill_with_objects(obj_top, word_fill_size);
247 } else if (word_fill_size > 0) {
248 // We have space to fill, but we cannot fit an object there.
249 words_not_fillable = word_fill_size;
250 word_fill_size = 0;
251 }
252
253 // We will set up the first region as "starts humongous". This
254 // will also update the BOT covering all the regions to reflect
255 // that there is a single object that starts at the bottom of the
256 // first region.
257 first_hr->set_starts_humongous(obj_top, word_fill_size);
258 _g1_policy->remset_tracker()->update_at_allocate(first_hr);
259 // Then, if there are any, we will set up the "continues
260 // humongous" regions.
261 HeapRegion* hr = NULL;
262 for (uint i = first + 1; i <= last; ++i) {
263 hr = region_at(i);
264 hr->set_continues_humongous(first_hr);
265 _g1_policy->remset_tracker()->update_at_allocate(hr);
266 }
267
268 // Up to this point no concurrent thread would have been able to
269 // do any scanning on any region in this series. All the top
270 // fields still point to bottom, so the intersection between
271 // [bottom,top] and [card_start,card_end] will be empty. Before we
272 // update the top fields, we'll do a storestore to make sure that
273 // no thread sees the update to top before the zeroing of the
274 // object header and the BOT initialization.
275 OrderAccess::storestore();
276
277 // Now, we will update the top fields of the "continues humongous"
278 // regions except the last one.
279 for (uint i = first; i < last; ++i) {
280 hr = region_at(i);
281 hr->set_top(hr->end());
282 }
283
284 hr = region_at(last);
285 // If we cannot fit a filler object, we must set top to the end
286 // of the humongous object, otherwise we cannot iterate the heap
287 // and the BOT will not be complete.
288 hr->set_top(hr->end() - words_not_fillable);
289
290 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
291 "obj_top should be in last region");
292
293 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
294
295 assert(words_not_fillable == 0 ||
296 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
297 "Miscalculation in humongous allocation");
298
299 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
300
301 for (uint i = first; i <= last; ++i) {
302 hr = region_at(i);
303 _humongous_set.add(hr);
304 _hr_printer.alloc(hr);
305 }
306
307 return new_obj;
308 }
309
310 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
311 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
312 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
313 }
314
315 // If could fit into free regions w/o expansion, try.
316 // Otherwise, if can expand, do so.
317 // Otherwise, if using ex regions might help, try with ex given back.
318 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
319 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
320
321 _verifier->verify_region_sets_optional();
322
323 uint first = G1_NO_HRM_INDEX;
324 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
325
326 if (obj_regions == 1) {
327 // Only one region to allocate, try to use a fast path by directly allocating
328 // from the free lists. Do not try to expand here, we will potentially do that
329 // later.
330 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
331 if (hr != NULL) {
332 first = hr->hrm_index();
333 }
334 } else {
335 // Policy: Try only empty regions (i.e. already committed first). Maybe we
336 // are lucky enough to find some.
337 first = _hrm.find_contiguous_only_empty(obj_regions);
338 if (first != G1_NO_HRM_INDEX) {
339 _hrm.allocate_free_regions_starting_at(first, obj_regions);
340 }
341 }
342
343 if (first == G1_NO_HRM_INDEX) {
344 // Policy: We could not find enough regions for the humongous object in the
345 // free list. Look through the heap to find a mix of free and uncommitted regions.
346 // If so, try expansion.
347 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
348 if (first != G1_NO_HRM_INDEX) {
349 // We found something. Make sure these regions are committed, i.e. expand
350 // the heap. Alternatively we could do a defragmentation GC.
351 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
352 word_size * HeapWordSize);
353
354 _hrm.expand_at(first, obj_regions, workers());
355 g1_policy()->record_new_heap_size(num_regions());
356
357 #ifdef ASSERT
358 for (uint i = first; i < first + obj_regions; ++i) {
359 HeapRegion* hr = region_at(i);
360 assert(hr->is_free(), "sanity");
361 assert(hr->is_empty(), "sanity");
362 assert(is_on_master_free_list(hr), "sanity");
363 }
364 #endif
365 _hrm.allocate_free_regions_starting_at(first, obj_regions);
366 } else {
367 // Policy: Potentially trigger a defragmentation GC.
368 }
369 }
370
371 HeapWord* result = NULL;
372 if (first != G1_NO_HRM_INDEX) {
373 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
374 assert(result != NULL, "it should always return a valid result");
375
376 // A successful humongous object allocation changes the used space
377 // information of the old generation so we need to recalculate the
378 // sizes and update the jstat counters here.
379 g1mm()->update_sizes();
380 }
381
382 _verifier->verify_region_sets_optional();
383
384 return result;
385 }
386
387 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
388 size_t requested_size,
389 size_t* actual_size) {
390 assert_heap_not_locked_and_not_at_safepoint();
391 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
392
393 return attempt_allocation(min_size, requested_size, actual_size);
394 }
395
396 HeapWord*
397 G1CollectedHeap::mem_allocate(size_t word_size,
398 bool* gc_overhead_limit_was_exceeded) {
399 assert_heap_not_locked_and_not_at_safepoint();
400
401 if (is_humongous(word_size)) {
402 return attempt_allocation_humongous(word_size);
403 }
404 size_t dummy = 0;
405 return attempt_allocation(word_size, word_size, &dummy);
406 }
407
408 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
409 ResourceMark rm; // For retrieving the thread names in log messages.
410
411 // Make sure you read the note in attempt_allocation_humongous().
412
413 assert_heap_not_locked_and_not_at_safepoint();
414 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
415 "be called for humongous allocation requests");
416
417 // We should only get here after the first-level allocation attempt
418 // (attempt_allocation()) failed to allocate.
419
420 // We will loop until a) we manage to successfully perform the
421 // allocation or b) we successfully schedule a collection which
422 // fails to perform the allocation. b) is the only case when we'll
423 // return NULL.
424 HeapWord* result = NULL;
425 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
426 bool should_try_gc;
427 uint gc_count_before;
428
429 {
430 MutexLockerEx x(Heap_lock);
431 result = _allocator->attempt_allocation_locked(word_size);
432 if (result != NULL) {
433 return result;
434 }
435
436 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
437 // This is different to when only GCLocker::needs_gc() is set: try to avoid
438 // waiting because the GCLocker is active to not wait too long.
439 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
440 // No need for an ergo message here, can_expand_young_list() does this when
441 // it returns true.
442 result = _allocator->attempt_allocation_force(word_size);
443 if (result != NULL) {
444 return result;
445 }
446 }
447 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
448 // the GCLocker initiated GC has been performed and then retry. This includes
449 // the case when the GC Locker is not active but has not been performed.
450 should_try_gc = !GCLocker::needs_gc();
451 // Read the GC count while still holding the Heap_lock.
452 gc_count_before = total_collections();
453 }
454
455 if (should_try_gc) {
456 bool succeeded;
457 result = do_collection_pause(word_size, gc_count_before, &succeeded,
458 GCCause::_g1_inc_collection_pause);
459 if (result != NULL) {
460 assert(succeeded, "only way to get back a non-NULL result");
461 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
462 Thread::current()->name(), p2i(result));
463 return result;
464 }
465
466 if (succeeded) {
467 // We successfully scheduled a collection which failed to allocate. No
468 // point in trying to allocate further. We'll just return NULL.
469 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
470 SIZE_FORMAT " words", Thread::current()->name(), word_size);
471 return NULL;
472 }
473 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
474 Thread::current()->name(), word_size);
475 } else {
476 // Failed to schedule a collection.
477 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
478 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
479 SIZE_FORMAT " words", Thread::current()->name(), word_size);
480 return NULL;
481 }
482 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
483 // The GCLocker is either active or the GCLocker initiated
484 // GC has not yet been performed. Stall until it is and
485 // then retry the allocation.
486 GCLocker::stall_until_clear();
487 gclocker_retry_count += 1;
488 }
489
490 // We can reach here if we were unsuccessful in scheduling a
491 // collection (because another thread beat us to it) or if we were
492 // stalled due to the GC locker. In either can we should retry the
493 // allocation attempt in case another thread successfully
494 // performed a collection and reclaimed enough space. We do the
495 // first attempt (without holding the Heap_lock) here and the
496 // follow-on attempt will be at the start of the next loop
497 // iteration (after taking the Heap_lock).
498 size_t dummy = 0;
499 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
500 if (result != NULL) {
501 return result;
502 }
503
504 // Give a warning if we seem to be looping forever.
505 if ((QueuedAllocationWarningCount > 0) &&
506 (try_count % QueuedAllocationWarningCount == 0)) {
507 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
508 Thread::current()->name(), try_count, word_size);
509 }
510 }
511
512 ShouldNotReachHere();
513 return NULL;
514 }
515
516 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
517 assert_at_safepoint_on_vm_thread();
518 if (_archive_allocator == NULL) {
519 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
520 }
521 }
522
523 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
524 // Allocations in archive regions cannot be of a size that would be considered
525 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
526 // may be different at archive-restore time.
527 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
528 }
529
530 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
531 assert_at_safepoint_on_vm_thread();
532 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
533 if (is_archive_alloc_too_large(word_size)) {
534 return NULL;
535 }
536 return _archive_allocator->archive_mem_allocate(word_size);
537 }
538
539 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
540 size_t end_alignment_in_bytes) {
541 assert_at_safepoint_on_vm_thread();
542 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
543
544 // Call complete_archive to do the real work, filling in the MemRegion
545 // array with the archive regions.
546 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
547 delete _archive_allocator;
548 _archive_allocator = NULL;
549 }
550
551 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
552 assert(ranges != NULL, "MemRegion array NULL");
553 assert(count != 0, "No MemRegions provided");
554 MemRegion reserved = _hrm.reserved();
555 for (size_t i = 0; i < count; i++) {
556 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
557 return false;
558 }
559 }
560 return true;
561 }
562
563 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
564 size_t count,
565 bool open) {
566 assert(!is_init_completed(), "Expect to be called at JVM init time");
567 assert(ranges != NULL, "MemRegion array NULL");
568 assert(count != 0, "No MemRegions provided");
569 MutexLockerEx x(Heap_lock);
570
571 MemRegion reserved = _hrm.reserved();
572 HeapWord* prev_last_addr = NULL;
573 HeapRegion* prev_last_region = NULL;
574
575 // Temporarily disable pretouching of heap pages. This interface is used
576 // when mmap'ing archived heap data in, so pre-touching is wasted.
577 FlagSetting fs(AlwaysPreTouch, false);
578
579 // Enable archive object checking used by G1MarkSweep. We have to let it know
580 // about each archive range, so that objects in those ranges aren't marked.
581 G1ArchiveAllocator::enable_archive_object_check();
582
583 // For each specified MemRegion range, allocate the corresponding G1
584 // regions and mark them as archive regions. We expect the ranges
585 // in ascending starting address order, without overlap.
586 for (size_t i = 0; i < count; i++) {
587 MemRegion curr_range = ranges[i];
588 HeapWord* start_address = curr_range.start();
589 size_t word_size = curr_range.word_size();
590 HeapWord* last_address = curr_range.last();
591 size_t commits = 0;
592
593 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
594 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
595 p2i(start_address), p2i(last_address));
596 guarantee(start_address > prev_last_addr,
597 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
598 p2i(start_address), p2i(prev_last_addr));
599 prev_last_addr = last_address;
600
601 // Check for ranges that start in the same G1 region in which the previous
602 // range ended, and adjust the start address so we don't try to allocate
603 // the same region again. If the current range is entirely within that
604 // region, skip it, just adjusting the recorded top.
605 HeapRegion* start_region = _hrm.addr_to_region(start_address);
606 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
607 start_address = start_region->end();
608 if (start_address > last_address) {
609 increase_used(word_size * HeapWordSize);
610 start_region->set_top(last_address + 1);
611 continue;
612 }
613 start_region->set_top(start_address);
614 curr_range = MemRegion(start_address, last_address + 1);
615 start_region = _hrm.addr_to_region(start_address);
616 }
617
618 // Perform the actual region allocation, exiting if it fails.
619 // Then note how much new space we have allocated.
620 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
621 return false;
622 }
623 increase_used(word_size * HeapWordSize);
624 if (commits != 0) {
625 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
626 HeapRegion::GrainWords * HeapWordSize * commits);
627
628 }
629
630 // Mark each G1 region touched by the range as archive, add it to
631 // the old set, and set top.
632 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
633 HeapRegion* last_region = _hrm.addr_to_region(last_address);
634 prev_last_region = last_region;
635
636 while (curr_region != NULL) {
637 assert(curr_region->is_empty() && !curr_region->is_pinned(),
638 "Region already in use (index %u)", curr_region->hrm_index());
639 if (open) {
640 curr_region->set_open_archive();
641 } else {
642 curr_region->set_closed_archive();
643 }
644 _hr_printer.alloc(curr_region);
645 _old_set.add(curr_region);
646 HeapWord* top;
647 HeapRegion* next_region;
648 if (curr_region != last_region) {
649 top = curr_region->end();
650 next_region = _hrm.next_region_in_heap(curr_region);
651 } else {
652 top = last_address + 1;
653 next_region = NULL;
654 }
655 curr_region->set_top(top);
656 curr_region->set_first_dead(top);
657 curr_region->set_end_of_live(top);
658 curr_region = next_region;
659 }
660
661 // Notify mark-sweep of the archive
662 G1ArchiveAllocator::set_range_archive(curr_range, open);
663 }
664 return true;
665 }
666
667 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
668 assert(!is_init_completed(), "Expect to be called at JVM init time");
669 assert(ranges != NULL, "MemRegion array NULL");
670 assert(count != 0, "No MemRegions provided");
671 MemRegion reserved = _hrm.reserved();
672 HeapWord *prev_last_addr = NULL;
673 HeapRegion* prev_last_region = NULL;
674
675 // For each MemRegion, create filler objects, if needed, in the G1 regions
676 // that contain the address range. The address range actually within the
677 // MemRegion will not be modified. That is assumed to have been initialized
678 // elsewhere, probably via an mmap of archived heap data.
679 MutexLockerEx x(Heap_lock);
680 for (size_t i = 0; i < count; i++) {
681 HeapWord* start_address = ranges[i].start();
682 HeapWord* last_address = ranges[i].last();
683
684 assert(reserved.contains(start_address) && reserved.contains(last_address),
685 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
686 p2i(start_address), p2i(last_address));
687 assert(start_address > prev_last_addr,
688 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
689 p2i(start_address), p2i(prev_last_addr));
690
691 HeapRegion* start_region = _hrm.addr_to_region(start_address);
692 HeapRegion* last_region = _hrm.addr_to_region(last_address);
693 HeapWord* bottom_address = start_region->bottom();
694
695 // Check for a range beginning in the same region in which the
696 // previous one ended.
697 if (start_region == prev_last_region) {
698 bottom_address = prev_last_addr + 1;
699 }
700
701 // Verify that the regions were all marked as archive regions by
702 // alloc_archive_regions.
703 HeapRegion* curr_region = start_region;
704 while (curr_region != NULL) {
705 guarantee(curr_region->is_archive(),
706 "Expected archive region at index %u", curr_region->hrm_index());
707 if (curr_region != last_region) {
708 curr_region = _hrm.next_region_in_heap(curr_region);
709 } else {
710 curr_region = NULL;
711 }
712 }
713
714 prev_last_addr = last_address;
715 prev_last_region = last_region;
716
717 // Fill the memory below the allocated range with dummy object(s),
718 // if the region bottom does not match the range start, or if the previous
719 // range ended within the same G1 region, and there is a gap.
720 if (start_address != bottom_address) {
721 size_t fill_size = pointer_delta(start_address, bottom_address);
722 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
723 increase_used(fill_size * HeapWordSize);
724 }
725 }
726 }
727
728 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
729 size_t desired_word_size,
730 size_t* actual_word_size) {
731 assert_heap_not_locked_and_not_at_safepoint();
732 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
733 "be called for humongous allocation requests");
734
735 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
736
737 if (result == NULL) {
738 *actual_word_size = desired_word_size;
739 result = attempt_allocation_slow(desired_word_size);
740 }
741
742 assert_heap_not_locked();
743 if (result != NULL) {
744 assert(*actual_word_size != 0, "Actual size must have been set here");
745 dirty_young_block(result, *actual_word_size);
746 } else {
747 *actual_word_size = 0;
748 }
749
750 return result;
751 }
752
753 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
754 assert(!is_init_completed(), "Expect to be called at JVM init time");
755 assert(ranges != NULL, "MemRegion array NULL");
756 assert(count != 0, "No MemRegions provided");
757 MemRegion reserved = _hrm.reserved();
758 HeapWord* prev_last_addr = NULL;
759 HeapRegion* prev_last_region = NULL;
760 size_t size_used = 0;
761 size_t uncommitted_regions = 0;
762
763 // For each Memregion, free the G1 regions that constitute it, and
764 // notify mark-sweep that the range is no longer to be considered 'archive.'
765 MutexLockerEx x(Heap_lock);
766 for (size_t i = 0; i < count; i++) {
767 HeapWord* start_address = ranges[i].start();
768 HeapWord* last_address = ranges[i].last();
769
770 assert(reserved.contains(start_address) && reserved.contains(last_address),
771 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
772 p2i(start_address), p2i(last_address));
773 assert(start_address > prev_last_addr,
774 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
775 p2i(start_address), p2i(prev_last_addr));
776 size_used += ranges[i].byte_size();
777 prev_last_addr = last_address;
778
779 HeapRegion* start_region = _hrm.addr_to_region(start_address);
780 HeapRegion* last_region = _hrm.addr_to_region(last_address);
781
782 // Check for ranges that start in the same G1 region in which the previous
783 // range ended, and adjust the start address so we don't try to free
784 // the same region again. If the current range is entirely within that
785 // region, skip it.
786 if (start_region == prev_last_region) {
787 start_address = start_region->end();
788 if (start_address > last_address) {
789 continue;
790 }
791 start_region = _hrm.addr_to_region(start_address);
792 }
793 prev_last_region = last_region;
794
795 // After verifying that each region was marked as an archive region by
796 // alloc_archive_regions, set it free and empty and uncommit it.
797 HeapRegion* curr_region = start_region;
798 while (curr_region != NULL) {
799 guarantee(curr_region->is_archive(),
800 "Expected archive region at index %u", curr_region->hrm_index());
801 uint curr_index = curr_region->hrm_index();
802 _old_set.remove(curr_region);
803 curr_region->set_free();
804 curr_region->set_top(curr_region->bottom());
805 if (curr_region != last_region) {
806 curr_region = _hrm.next_region_in_heap(curr_region);
807 } else {
808 curr_region = NULL;
809 }
810 _hrm.shrink_at(curr_index, 1);
811 uncommitted_regions++;
812 }
813
814 // Notify mark-sweep that this is no longer an archive range.
815 G1ArchiveAllocator::set_range_archive(ranges[i], false);
816 }
817
818 if (uncommitted_regions != 0) {
819 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
820 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
821 }
822 decrease_used(size_used);
823 }
824
825 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
826 ResourceMark rm; // For retrieving the thread names in log messages.
827
828 // The structure of this method has a lot of similarities to
829 // attempt_allocation_slow(). The reason these two were not merged
830 // into a single one is that such a method would require several "if
831 // allocation is not humongous do this, otherwise do that"
832 // conditional paths which would obscure its flow. In fact, an early
833 // version of this code did use a unified method which was harder to
834 // follow and, as a result, it had subtle bugs that were hard to
835 // track down. So keeping these two methods separate allows each to
836 // be more readable. It will be good to keep these two in sync as
837 // much as possible.
838
839 assert_heap_not_locked_and_not_at_safepoint();
840 assert(is_humongous(word_size), "attempt_allocation_humongous() "
841 "should only be called for humongous allocations");
842
843 // Humongous objects can exhaust the heap quickly, so we should check if we
844 // need to start a marking cycle at each humongous object allocation. We do
845 // the check before we do the actual allocation. The reason for doing it
846 // before the allocation is that we avoid having to keep track of the newly
847 // allocated memory while we do a GC.
848 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
849 word_size)) {
850 collect(GCCause::_g1_humongous_allocation);
851 }
852
853 // We will loop until a) we manage to successfully perform the
854 // allocation or b) we successfully schedule a collection which
855 // fails to perform the allocation. b) is the only case when we'll
856 // return NULL.
857 HeapWord* result = NULL;
858 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
859 bool should_try_gc;
860 uint gc_count_before;
861
862
863 {
864 MutexLockerEx x(Heap_lock);
865
866 // Given that humongous objects are not allocated in young
867 // regions, we'll first try to do the allocation without doing a
868 // collection hoping that there's enough space in the heap.
869 result = humongous_obj_allocate(word_size);
870 if (result != NULL) {
871 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
872 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
873 return result;
874 }
875
876 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
877 // the GCLocker initiated GC has been performed and then retry. This includes
878 // the case when the GC Locker is not active but has not been performed.
879 should_try_gc = !GCLocker::needs_gc();
880 // Read the GC count while still holding the Heap_lock.
881 gc_count_before = total_collections();
882 }
883
884 if (should_try_gc) {
885 bool succeeded;
886 result = do_collection_pause(word_size, gc_count_before, &succeeded,
887 GCCause::_g1_humongous_allocation);
888 if (result != NULL) {
889 assert(succeeded, "only way to get back a non-NULL result");
890 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
891 Thread::current()->name(), p2i(result));
892 return result;
893 }
894
895 if (succeeded) {
896 // We successfully scheduled a collection which failed to allocate. No
897 // point in trying to allocate further. We'll just return NULL.
898 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
899 SIZE_FORMAT " words", Thread::current()->name(), word_size);
900 return NULL;
901 }
902 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
903 Thread::current()->name(), word_size);
904 } else {
905 // Failed to schedule a collection.
906 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
907 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
908 SIZE_FORMAT " words", Thread::current()->name(), word_size);
909 return NULL;
910 }
911 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
912 // The GCLocker is either active or the GCLocker initiated
913 // GC has not yet been performed. Stall until it is and
914 // then retry the allocation.
915 GCLocker::stall_until_clear();
916 gclocker_retry_count += 1;
917 }
918
919
920 // We can reach here if we were unsuccessful in scheduling a
921 // collection (because another thread beat us to it) or if we were
922 // stalled due to the GC locker. In either can we should retry the
923 // allocation attempt in case another thread successfully
924 // performed a collection and reclaimed enough space.
925 // Humongous object allocation always needs a lock, so we wait for the retry
926 // in the next iteration of the loop, unlike for the regular iteration case.
927 // Give a warning if we seem to be looping forever.
928
929 if ((QueuedAllocationWarningCount > 0) &&
930 (try_count % QueuedAllocationWarningCount == 0)) {
931 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
932 Thread::current()->name(), try_count, word_size);
933 }
934 }
935
936 ShouldNotReachHere();
937 return NULL;
938 }
939
940 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
941 bool expect_null_mutator_alloc_region) {
942 assert_at_safepoint_on_vm_thread();
943 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
944 "the current alloc region was unexpectedly found to be non-NULL");
945
946 if (!is_humongous(word_size)) {
947 return _allocator->attempt_allocation_locked(word_size);
948 } else {
949 HeapWord* result = humongous_obj_allocate(word_size);
950 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
951 collector_state()->set_initiate_conc_mark_if_possible(true);
952 }
953 return result;
954 }
955
956 ShouldNotReachHere();
957 }
958
959 class PostCompactionPrinterClosure: public HeapRegionClosure {
960 private:
961 G1HRPrinter* _hr_printer;
962 public:
963 bool do_heap_region(HeapRegion* hr) {
964 assert(!hr->is_young(), "not expecting to find young regions");
965 _hr_printer->post_compaction(hr);
966 return false;
967 }
968
969 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
970 : _hr_printer(hr_printer) { }
971 };
972
973 void G1CollectedHeap::print_hrm_post_compaction() {
974 if (_hr_printer.is_active()) {
975 PostCompactionPrinterClosure cl(hr_printer());
976 heap_region_iterate(&cl);
977 }
978 }
979
980 void G1CollectedHeap::abort_concurrent_cycle() {
981 // If we start the compaction before the CM threads finish
982 // scanning the root regions we might trip them over as we'll
983 // be moving objects / updating references. So let's wait until
984 // they are done. By telling them to abort, they should complete
985 // early.
986 _cm->root_regions()->abort();
987 _cm->root_regions()->wait_until_scan_finished();
988
989 // Disable discovery and empty the discovered lists
990 // for the CM ref processor.
991 _ref_processor_cm->disable_discovery();
992 _ref_processor_cm->abandon_partial_discovery();
993 _ref_processor_cm->verify_no_references_recorded();
994
995 // Abandon current iterations of concurrent marking and concurrent
996 // refinement, if any are in progress.
997 concurrent_mark()->concurrent_cycle_abort();
998 }
999
1000 void G1CollectedHeap::prepare_heap_for_full_collection() {
1001 // Make sure we'll choose a new allocation region afterwards.
1002 _allocator->release_mutator_alloc_region();
1003 _allocator->abandon_gc_alloc_regions();
1004 g1_rem_set()->cleanupHRRS();
1005
1006 // We may have added regions to the current incremental collection
1007 // set between the last GC or pause and now. We need to clear the
1008 // incremental collection set and then start rebuilding it afresh
1009 // after this full GC.
1010 abandon_collection_set(collection_set());
1011
1012 tear_down_region_sets(false /* free_list_only */);
1013 }
1014
1015 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1016 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1017 assert(used() == recalculate_used(), "Should be equal");
1018 _verifier->verify_region_sets_optional();
1019 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1020 _verifier->check_bitmaps("Full GC Start");
1021 }
1022
1023 void G1CollectedHeap::prepare_heap_for_mutators() {
1024 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1025 ClassLoaderDataGraph::purge();
1026 MetaspaceUtils::verify_metrics();
1027
1028 // Prepare heap for normal collections.
1029 assert(num_free_regions() == 0, "we should not have added any free regions");
1030 rebuild_region_sets(false /* free_list_only */);
1031 abort_refinement();
1032 resize_if_necessary_after_full_collection();
1033
1034 // Rebuild the strong code root lists for each region
1035 rebuild_strong_code_roots();
1036
1037 // Start a new incremental collection set for the next pause
1038 start_new_collection_set();
1039
1040 _allocator->init_mutator_alloc_region();
1041
1042 // Post collection state updates.
1043 MetaspaceGC::compute_new_size();
1044 }
1045
1046 void G1CollectedHeap::abort_refinement() {
1047 if (_hot_card_cache->use_cache()) {
1048 _hot_card_cache->reset_hot_cache();
1049 }
1050
1051 // Discard all remembered set updates.
1052 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1053 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1054 }
1055
1056 void G1CollectedHeap::verify_after_full_collection() {
1057 _hrm.verify_optional();
1058 _verifier->verify_region_sets_optional();
1059 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1060 // Clear the previous marking bitmap, if needed for bitmap verification.
1061 // Note we cannot do this when we clear the next marking bitmap in
1062 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1063 // objects marked during a full GC against the previous bitmap.
1064 // But we need to clear it before calling check_bitmaps below since
1065 // the full GC has compacted objects and updated TAMS but not updated
1066 // the prev bitmap.
1067 if (G1VerifyBitmaps) {
1068 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1069 _cm->clear_prev_bitmap(workers());
1070 }
1071 _verifier->check_bitmaps("Full GC End");
1072
1073 // At this point there should be no regions in the
1074 // entire heap tagged as young.
1075 assert(check_young_list_empty(), "young list should be empty at this point");
1076
1077 // Note: since we've just done a full GC, concurrent
1078 // marking is no longer active. Therefore we need not
1079 // re-enable reference discovery for the CM ref processor.
1080 // That will be done at the start of the next marking cycle.
1081 // We also know that the STW processor should no longer
1082 // discover any new references.
1083 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1084 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1085 _ref_processor_stw->verify_no_references_recorded();
1086 _ref_processor_cm->verify_no_references_recorded();
1087 }
1088
1089 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1090 // Post collection logging.
1091 // We should do this after we potentially resize the heap so
1092 // that all the COMMIT / UNCOMMIT events are generated before
1093 // the compaction events.
1094 print_hrm_post_compaction();
1095 heap_transition->print();
1096 print_heap_after_gc();
1097 print_heap_regions();
1098 #ifdef TRACESPINNING
1099 ParallelTaskTerminator::print_termination_counts();
1100 #endif
1101 }
1102
1103 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1104 bool clear_all_soft_refs) {
1105 assert_at_safepoint_on_vm_thread();
1106
1107 if (GCLocker::check_active_before_gc()) {
1108 // Full GC was not completed.
1109 return false;
1110 }
1111
1112 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1113 soft_ref_policy()->should_clear_all_soft_refs();
1114
1115 G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1116 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1117
1118 collector.prepare_collection();
1119 collector.collect();
1120 collector.complete_collection();
1121
1122 // Full collection was successfully completed.
1123 return true;
1124 }
1125
1126 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1127 // Currently, there is no facility in the do_full_collection(bool) API to notify
1128 // the caller that the collection did not succeed (e.g., because it was locked
1129 // out by the GC locker). So, right now, we'll ignore the return value.
1130 bool dummy = do_full_collection(true, /* explicit_gc */
1131 clear_all_soft_refs);
1132 }
1133
1134 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1135 // Capacity, free and used after the GC counted as full regions to
1136 // include the waste in the following calculations.
1137 const size_t capacity_after_gc = capacity();
1138 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1139
1140 // This is enforced in arguments.cpp.
1141 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1142 "otherwise the code below doesn't make sense");
1143
1144 // We don't have floating point command-line arguments
1145 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1146 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1147 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1148 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1149
1150 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1151 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1152
1153 // We have to be careful here as these two calculations can overflow
1154 // 32-bit size_t's.
1155 double used_after_gc_d = (double) used_after_gc;
1156 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1157 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1158
1159 // Let's make sure that they are both under the max heap size, which
1160 // by default will make them fit into a size_t.
1161 double desired_capacity_upper_bound = (double) max_heap_size;
1162 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1163 desired_capacity_upper_bound);
1164 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1165 desired_capacity_upper_bound);
1166
1167 // We can now safely turn them into size_t's.
1168 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1169 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1170
1171 // This assert only makes sense here, before we adjust them
1172 // with respect to the min and max heap size.
1173 assert(minimum_desired_capacity <= maximum_desired_capacity,
1174 "minimum_desired_capacity = " SIZE_FORMAT ", "
1175 "maximum_desired_capacity = " SIZE_FORMAT,
1176 minimum_desired_capacity, maximum_desired_capacity);
1177
1178 // Should not be greater than the heap max size. No need to adjust
1179 // it with respect to the heap min size as it's a lower bound (i.e.,
1180 // we'll try to make the capacity larger than it, not smaller).
1181 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1182 // Should not be less than the heap min size. No need to adjust it
1183 // with respect to the heap max size as it's an upper bound (i.e.,
1184 // we'll try to make the capacity smaller than it, not greater).
1185 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1186
1187 if (capacity_after_gc < minimum_desired_capacity) {
1188 // Don't expand unless it's significant
1189 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1190
1191 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1192 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1193 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1194 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1195
1196 expand(expand_bytes, _workers);
1197
1198 // No expansion, now see if we want to shrink
1199 } else if (capacity_after_gc > maximum_desired_capacity) {
1200 // Capacity too large, compute shrinking size
1201 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1202
1203 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1204 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1205 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1206 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1207
1208 shrink(shrink_bytes);
1209 }
1210 }
1211
1212 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1213 bool do_gc,
1214 bool clear_all_soft_refs,
1215 bool expect_null_mutator_alloc_region,
1216 bool* gc_succeeded) {
1217 *gc_succeeded = true;
1218 // Let's attempt the allocation first.
1219 HeapWord* result =
1220 attempt_allocation_at_safepoint(word_size,
1221 expect_null_mutator_alloc_region);
1222 if (result != NULL) {
1223 return result;
1224 }
1225
1226 // In a G1 heap, we're supposed to keep allocation from failing by
1227 // incremental pauses. Therefore, at least for now, we'll favor
1228 // expansion over collection. (This might change in the future if we can
1229 // do something smarter than full collection to satisfy a failed alloc.)
1230 result = expand_and_allocate(word_size);
1231 if (result != NULL) {
1232 return result;
1233 }
1234
1235 if (do_gc) {
1236 // Expansion didn't work, we'll try to do a Full GC.
1237 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1238 clear_all_soft_refs);
1239 }
1240
1241 return NULL;
1242 }
1243
1244 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1245 bool* succeeded) {
1246 assert_at_safepoint_on_vm_thread();
1247
1248 // Attempts to allocate followed by Full GC.
1249 HeapWord* result =
1250 satisfy_failed_allocation_helper(word_size,
1251 true, /* do_gc */
1252 false, /* clear_all_soft_refs */
1253 false, /* expect_null_mutator_alloc_region */
1254 succeeded);
1255
1256 if (result != NULL || !*succeeded) {
1257 return result;
1258 }
1259
1260 // Attempts to allocate followed by Full GC that will collect all soft references.
1261 result = satisfy_failed_allocation_helper(word_size,
1262 true, /* do_gc */
1263 true, /* clear_all_soft_refs */
1264 true, /* expect_null_mutator_alloc_region */
1265 succeeded);
1266
1267 if (result != NULL || !*succeeded) {
1268 return result;
1269 }
1270
1271 // Attempts to allocate, no GC
1272 result = satisfy_failed_allocation_helper(word_size,
1273 false, /* do_gc */
1274 false, /* clear_all_soft_refs */
1275 true, /* expect_null_mutator_alloc_region */
1276 succeeded);
1277
1278 if (result != NULL) {
1279 return result;
1280 }
1281
1282 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1283 "Flag should have been handled and cleared prior to this point");
1284
1285 // What else? We might try synchronous finalization later. If the total
1286 // space available is large enough for the allocation, then a more
1287 // complete compaction phase than we've tried so far might be
1288 // appropriate.
1289 return NULL;
1290 }
1291
1292 // Attempting to expand the heap sufficiently
1293 // to support an allocation of the given "word_size". If
1294 // successful, perform the allocation and return the address of the
1295 // allocated block, or else "NULL".
1296
1297 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1298 assert_at_safepoint_on_vm_thread();
1299
1300 _verifier->verify_region_sets_optional();
1301
1302 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1303 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1304 word_size * HeapWordSize);
1305
1306
1307 if (expand(expand_bytes, _workers)) {
1308 _hrm.verify_optional();
1309 _verifier->verify_region_sets_optional();
1310 return attempt_allocation_at_safepoint(word_size,
1311 false /* expect_null_mutator_alloc_region */);
1312 }
1313 return NULL;
1314 }
1315
1316 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1317 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1318 aligned_expand_bytes = align_up(aligned_expand_bytes,
1319 HeapRegion::GrainBytes);
1320
1321 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1322 expand_bytes, aligned_expand_bytes);
1323
1324 if (is_maximal_no_gc()) {
1325 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1326 return false;
1327 }
1328
1329 double expand_heap_start_time_sec = os::elapsedTime();
1330 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1331 assert(regions_to_expand > 0, "Must expand by at least one region");
1332
1333 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1334 if (expand_time_ms != NULL) {
1335 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1336 }
1337
1338 if (expanded_by > 0) {
1339 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1340 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1341 g1_policy()->record_new_heap_size(num_regions());
1342 } else {
1343 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1344
1345 // The expansion of the virtual storage space was unsuccessful.
1346 // Let's see if it was because we ran out of swap.
1347 if (G1ExitOnExpansionFailure &&
1348 _hrm.available() >= regions_to_expand) {
1349 // We had head room...
1350 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1351 }
1352 }
1353 return regions_to_expand > 0;
1354 }
1355
1356 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1357 size_t aligned_shrink_bytes =
1358 ReservedSpace::page_align_size_down(shrink_bytes);
1359 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1360 HeapRegion::GrainBytes);
1361 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1362
1363 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1364 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1365
1366
1367 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B",
1368 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1369 if (num_regions_removed > 0) {
1370 g1_policy()->record_new_heap_size(num_regions());
1371 } else {
1372 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1373 }
1374 }
1375
1376 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1377 _verifier->verify_region_sets_optional();
1378
1379 // We should only reach here at the end of a Full GC which means we
1380 // should not not be holding to any GC alloc regions. The method
1381 // below will make sure of that and do any remaining clean up.
1382 _allocator->abandon_gc_alloc_regions();
1383
1384 // Instead of tearing down / rebuilding the free lists here, we
1385 // could instead use the remove_all_pending() method on free_list to
1386 // remove only the ones that we need to remove.
1387 tear_down_region_sets(true /* free_list_only */);
1388 shrink_helper(shrink_bytes);
1389 rebuild_region_sets(true /* free_list_only */);
1390
1391 _hrm.verify_optional();
1392 _verifier->verify_region_sets_optional();
1393 }
1394
1395 // Public methods.
1396
1397 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1398 CollectedHeap(),
1399 _young_gen_sampling_thread(NULL),
1400 _collector_policy(collector_policy),
1401 _soft_ref_policy(),
1402 _card_table(NULL),
1403 _memory_manager("G1 Young Generation", "end of minor GC"),
1404 _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1405 _eden_pool(NULL),
1406 _survivor_pool(NULL),
1407 _old_pool(NULL),
1408 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1409 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1410 _g1_policy(new G1Policy(_gc_timer_stw)),
1411 _collection_set(this, _g1_policy),
1412 _dirty_card_queue_set(false),
1413 _ref_processor_stw(NULL),
1414 _is_alive_closure_stw(this),
1415 _is_subject_to_discovery_stw(this),
1416 _ref_processor_cm(NULL),
1417 _is_alive_closure_cm(this),
1418 _is_subject_to_discovery_cm(this),
1419 _bot(NULL),
1420 _hot_card_cache(NULL),
1421 _g1_rem_set(NULL),
1422 _cr(NULL),
1423 _g1mm(NULL),
1424 _preserved_marks_set(true /* in_c_heap */),
1425 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1426 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1427 _humongous_reclaim_candidates(),
1428 _has_humongous_reclaim_candidates(false),
1429 _archive_allocator(NULL),
1430 _summary_bytes_used(0),
1431 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1432 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1433 _expand_heap_after_alloc_failure(true),
1434 _old_marking_cycles_started(0),
1435 _old_marking_cycles_completed(0),
1436 _in_cset_fast_test() {
1437
1438 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1439 /* are_GC_task_threads */true,
1440 /* are_ConcurrentGC_threads */false);
1441 _workers->initialize_workers();
1442 _verifier = new G1HeapVerifier(this);
1443
1444 _allocator = new G1Allocator(this);
1445
1446 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1447
1448 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1449
1450 // Override the default _filler_array_max_size so that no humongous filler
1451 // objects are created.
1452 _filler_array_max_size = _humongous_object_threshold_in_words;
1453
1454 uint n_queues = ParallelGCThreads;
1455 _task_queues = new RefToScanQueueSet(n_queues);
1456
1457 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1458
1459 for (uint i = 0; i < n_queues; i++) {
1460 RefToScanQueue* q = new RefToScanQueue();
1461 q->initialize();
1462 _task_queues->register_queue(i, q);
1463 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1464 }
1465
1466 // Initialize the G1EvacuationFailureALot counters and flags.
1467 NOT_PRODUCT(reset_evacuation_should_fail();)
1468
1469 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1470 }
1471
1472 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1473 size_t size,
1474 size_t translation_factor) {
1475 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1476 // Allocate a new reserved space, preferring to use large pages.
1477 ReservedSpace rs(size, preferred_page_size);
1478 G1RegionToSpaceMapper* result =
1479 G1RegionToSpaceMapper::create_mapper(rs,
1480 size,
1481 rs.alignment(),
1482 HeapRegion::GrainBytes,
1483 translation_factor,
1484 mtGC);
1485
1486 os::trace_page_sizes_for_requested_size(description,
1487 size,
1488 preferred_page_size,
1489 rs.alignment(),
1490 rs.base(),
1491 rs.size());
1492
1493 return result;
1494 }
1495
1496 jint G1CollectedHeap::initialize_concurrent_refinement() {
1497 jint ecode = JNI_OK;
1498 _cr = G1ConcurrentRefine::create(&ecode);
1499 return ecode;
1500 }
1501
1502 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1503 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1504 if (_young_gen_sampling_thread->osthread() == NULL) {
1505 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1506 return JNI_ENOMEM;
1507 }
1508 return JNI_OK;
1509 }
1510
1511 jint G1CollectedHeap::initialize() {
1512 os::enable_vtime();
1513
1514 // Necessary to satisfy locking discipline assertions.
1515
1516 MutexLocker x(Heap_lock);
1517
1518 // While there are no constraints in the GC code that HeapWordSize
1519 // be any particular value, there are multiple other areas in the
1520 // system which believe this to be true (e.g. oop->object_size in some
1521 // cases incorrectly returns the size in wordSize units rather than
1522 // HeapWordSize).
1523 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1524
1525 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1526 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1527 size_t heap_alignment = collector_policy()->heap_alignment();
1528
1529 // Ensure that the sizes are properly aligned.
1530 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1531 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1532 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1533
1534 // Reserve the maximum.
1535
1536 // When compressed oops are enabled, the preferred heap base
1537 // is calculated by subtracting the requested size from the
1538 // 32Gb boundary and using the result as the base address for
1539 // heap reservation. If the requested size is not aligned to
1540 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1541 // into the ReservedHeapSpace constructor) then the actual
1542 // base of the reserved heap may end up differing from the
1543 // address that was requested (i.e. the preferred heap base).
1544 // If this happens then we could end up using a non-optimal
1545 // compressed oops mode.
1546
1547 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1548 heap_alignment);
1549
1550 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1551
1552 // Create the barrier set for the entire reserved region.
1553 G1CardTable* ct = new G1CardTable(reserved_region());
1554 ct->initialize();
1555 G1BarrierSet* bs = new G1BarrierSet(ct);
1556 bs->initialize();
1557 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1558 BarrierSet::set_barrier_set(bs);
1559 _card_table = ct;
1560
1561 // Create the hot card cache.
1562 _hot_card_cache = new G1HotCardCache(this);
1563
1564 // Carve out the G1 part of the heap.
1565 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1566 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1567 G1RegionToSpaceMapper* heap_storage =
1568 G1RegionToSpaceMapper::create_mapper(g1_rs,
1569 g1_rs.size(),
1570 page_size,
1571 HeapRegion::GrainBytes,
1572 1,
1573 mtJavaHeap);
1574 os::trace_page_sizes("Heap",
1575 collector_policy()->min_heap_byte_size(),
1576 max_byte_size,
1577 page_size,
1578 heap_rs.base(),
1579 heap_rs.size());
1580 heap_storage->set_mapping_changed_listener(&_listener);
1581
1582 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1583 G1RegionToSpaceMapper* bot_storage =
1584 create_aux_memory_mapper("Block Offset Table",
1585 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1586 G1BlockOffsetTable::heap_map_factor());
1587
1588 G1RegionToSpaceMapper* cardtable_storage =
1589 create_aux_memory_mapper("Card Table",
1590 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1591 G1CardTable::heap_map_factor());
1592
1593 G1RegionToSpaceMapper* card_counts_storage =
1594 create_aux_memory_mapper("Card Counts Table",
1595 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1596 G1CardCounts::heap_map_factor());
1597
1598 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1599 G1RegionToSpaceMapper* prev_bitmap_storage =
1600 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1601 G1RegionToSpaceMapper* next_bitmap_storage =
1602 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1603
1604 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1605 _card_table->initialize(cardtable_storage);
1606 // Do later initialization work for concurrent refinement.
1607 _hot_card_cache->initialize(card_counts_storage);
1608
1609 // 6843694 - ensure that the maximum region index can fit
1610 // in the remembered set structures.
1611 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1612 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1613
1614 // Also create a G1 rem set.
1615 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1616 _g1_rem_set->initialize(max_capacity(), max_regions());
1617
1618 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1619 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1620 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1621 "too many cards per region");
1622
1623 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1624
1625 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1626
1627 {
1628 HeapWord* start = _hrm.reserved().start();
1629 HeapWord* end = _hrm.reserved().end();
1630 size_t granularity = HeapRegion::GrainBytes;
1631
1632 _in_cset_fast_test.initialize(start, end, granularity);
1633 _humongous_reclaim_candidates.initialize(start, end, granularity);
1634 }
1635
1636 // Create the G1ConcurrentMark data structure and thread.
1637 // (Must do this late, so that "max_regions" is defined.)
1638 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1639 if (_cm == NULL || !_cm->completed_initialization()) {
1640 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1641 return JNI_ENOMEM;
1642 }
1643 _cm_thread = _cm->cm_thread();
1644
1645 // Now expand into the initial heap size.
1646 if (!expand(init_byte_size, _workers)) {
1647 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1648 return JNI_ENOMEM;
1649 }
1650
1651 // Perform any initialization actions delegated to the policy.
1652 g1_policy()->init(this, &_collection_set);
1653
1654 G1BarrierSet::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1655 SATB_Q_FL_lock,
1656 G1SATBProcessCompletedThreshold,
1657 Shared_SATB_Q_lock);
1658
1659 jint ecode = initialize_concurrent_refinement();
1660 if (ecode != JNI_OK) {
1661 return ecode;
1662 }
1663
1664 ecode = initialize_young_gen_sampling_thread();
1665 if (ecode != JNI_OK) {
1666 return ecode;
1667 }
1668
1669 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1670 DirtyCardQ_FL_lock,
1671 (int)concurrent_refine()->yellow_zone(),
1672 (int)concurrent_refine()->red_zone(),
1673 Shared_DirtyCardQ_lock,
1674 NULL, // fl_owner
1675 true); // init_free_ids
1676
1677 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1678 DirtyCardQ_FL_lock,
1679 -1, // never trigger processing
1680 -1, // no limit on length
1681 Shared_DirtyCardQ_lock,
1682 &G1BarrierSet::dirty_card_queue_set());
1683
1684 // Here we allocate the dummy HeapRegion that is required by the
1685 // G1AllocRegion class.
1686 HeapRegion* dummy_region = _hrm.get_dummy_region();
1687
1688 // We'll re-use the same region whether the alloc region will
1689 // require BOT updates or not and, if it doesn't, then a non-young
1690 // region will complain that it cannot support allocations without
1691 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1692 dummy_region->set_eden();
1693 // Make sure it's full.
1694 dummy_region->set_top(dummy_region->end());
1695 G1AllocRegion::setup(this, dummy_region);
1696
1697 _allocator->init_mutator_alloc_region();
1698
1699 // Do create of the monitoring and management support so that
1700 // values in the heap have been properly initialized.
1701 _g1mm = new G1MonitoringSupport(this);
1702
1703 G1StringDedup::initialize();
1704
1705 _preserved_marks_set.init(ParallelGCThreads);
1706
1707 _collection_set.initialize(max_regions());
1708
1709 return JNI_OK;
1710 }
1711
1712 void G1CollectedHeap::initialize_serviceability() {
1713 _eden_pool = new G1EdenPool(this);
1714 _survivor_pool = new G1SurvivorPool(this);
1715 _old_pool = new G1OldGenPool(this);
1716
1717 _full_gc_memory_manager.add_pool(_eden_pool);
1718 _full_gc_memory_manager.add_pool(_survivor_pool);
1719 _full_gc_memory_manager.add_pool(_old_pool);
1720
1721 _memory_manager.add_pool(_eden_pool);
1722 _memory_manager.add_pool(_survivor_pool);
1723
1724 }
1725
1726 void G1CollectedHeap::stop() {
1727 // Stop all concurrent threads. We do this to make sure these threads
1728 // do not continue to execute and access resources (e.g. logging)
1729 // that are destroyed during shutdown.
1730 _cr->stop();
1731 _young_gen_sampling_thread->stop();
1732 _cm_thread->stop();
1733 if (G1StringDedup::is_enabled()) {
1734 G1StringDedup::stop();
1735 }
1736 }
1737
1738 void G1CollectedHeap::safepoint_synchronize_begin() {
1739 SuspendibleThreadSet::synchronize();
1740 }
1741
1742 void G1CollectedHeap::safepoint_synchronize_end() {
1743 SuspendibleThreadSet::desynchronize();
1744 }
1745
1746 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1747 return HeapRegion::max_region_size();
1748 }
1749
1750 void G1CollectedHeap::post_initialize() {
1751 CollectedHeap::post_initialize();
1752 ref_processing_init();
1753 }
1754
1755 void G1CollectedHeap::ref_processing_init() {
1756 // Reference processing in G1 currently works as follows:
1757 //
1758 // * There are two reference processor instances. One is
1759 // used to record and process discovered references
1760 // during concurrent marking; the other is used to
1761 // record and process references during STW pauses
1762 // (both full and incremental).
1763 // * Both ref processors need to 'span' the entire heap as
1764 // the regions in the collection set may be dotted around.
1765 //
1766 // * For the concurrent marking ref processor:
1767 // * Reference discovery is enabled at initial marking.
1768 // * Reference discovery is disabled and the discovered
1769 // references processed etc during remarking.
1770 // * Reference discovery is MT (see below).
1771 // * Reference discovery requires a barrier (see below).
1772 // * Reference processing may or may not be MT
1773 // (depending on the value of ParallelRefProcEnabled
1774 // and ParallelGCThreads).
1775 // * A full GC disables reference discovery by the CM
1776 // ref processor and abandons any entries on it's
1777 // discovered lists.
1778 //
1779 // * For the STW processor:
1780 // * Non MT discovery is enabled at the start of a full GC.
1781 // * Processing and enqueueing during a full GC is non-MT.
1782 // * During a full GC, references are processed after marking.
1783 //
1784 // * Discovery (may or may not be MT) is enabled at the start
1785 // of an incremental evacuation pause.
1786 // * References are processed near the end of a STW evacuation pause.
1787 // * For both types of GC:
1788 // * Discovery is atomic - i.e. not concurrent.
1789 // * Reference discovery will not need a barrier.
1790
1791 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1792
1793 // Concurrent Mark ref processor
1794 _ref_processor_cm =
1795 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1796 mt_processing, // mt processing
1797 ParallelGCThreads, // degree of mt processing
1798 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1799 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1800 false, // Reference discovery is not atomic
1801 &_is_alive_closure_cm); // is alive closure
1802
1803 // STW ref processor
1804 _ref_processor_stw =
1805 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1806 mt_processing, // mt processing
1807 ParallelGCThreads, // degree of mt processing
1808 (ParallelGCThreads > 1), // mt discovery
1809 ParallelGCThreads, // degree of mt discovery
1810 true, // Reference discovery is atomic
1811 &_is_alive_closure_stw); // is alive closure
1812 }
1813
1814 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1815 return _collector_policy;
1816 }
1817
1818 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1819 return &_soft_ref_policy;
1820 }
1821
1822 size_t G1CollectedHeap::capacity() const {
1823 return _hrm.length() * HeapRegion::GrainBytes;
1824 }
1825
1826 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1827 return _hrm.total_free_bytes();
1828 }
1829
1830 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1831 _hot_card_cache->drain(cl, worker_i);
1832 }
1833
1834 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1835 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1836 size_t n_completed_buffers = 0;
1837 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1838 n_completed_buffers++;
1839 }
1840 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1841 dcqs.clear_n_completed_buffers();
1842 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1843 }
1844
1845 // Computes the sum of the storage used by the various regions.
1846 size_t G1CollectedHeap::used() const {
1847 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1848 if (_archive_allocator != NULL) {
1849 result += _archive_allocator->used();
1850 }
1851 return result;
1852 }
1853
1854 size_t G1CollectedHeap::used_unlocked() const {
1855 return _summary_bytes_used;
1856 }
1857
1858 class SumUsedClosure: public HeapRegionClosure {
1859 size_t _used;
1860 public:
1861 SumUsedClosure() : _used(0) {}
1862 bool do_heap_region(HeapRegion* r) {
1863 _used += r->used();
1864 return false;
1865 }
1866 size_t result() { return _used; }
1867 };
1868
1869 size_t G1CollectedHeap::recalculate_used() const {
1870 double recalculate_used_start = os::elapsedTime();
1871
1872 SumUsedClosure blk;
1873 heap_region_iterate(&blk);
1874
1875 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1876 return blk.result();
1877 }
1878
1879 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1880 switch (cause) {
1881 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1882 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1883 case GCCause::_wb_conc_mark: return true;
1884 default : return false;
1885 }
1886 }
1887
1888 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1889 switch (cause) {
1890 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
1891 case GCCause::_g1_humongous_allocation: return true;
1892 default: return is_user_requested_concurrent_full_gc(cause);
1893 }
1894 }
1895
1896 #ifndef PRODUCT
1897 void G1CollectedHeap::allocate_dummy_regions() {
1898 // Let's fill up most of the region
1899 size_t word_size = HeapRegion::GrainWords - 1024;
1900 // And as a result the region we'll allocate will be humongous.
1901 guarantee(is_humongous(word_size), "sanity");
1902
1903 // _filler_array_max_size is set to humongous object threshold
1904 // but temporarily change it to use CollectedHeap::fill_with_object().
1905 SizeTFlagSetting fs(_filler_array_max_size, word_size);
1906
1907 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1908 // Let's use the existing mechanism for the allocation
1909 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1910 if (dummy_obj != NULL) {
1911 MemRegion mr(dummy_obj, word_size);
1912 CollectedHeap::fill_with_object(mr);
1913 } else {
1914 // If we can't allocate once, we probably cannot allocate
1915 // again. Let's get out of the loop.
1916 break;
1917 }
1918 }
1919 }
1920 #endif // !PRODUCT
1921
1922 void G1CollectedHeap::increment_old_marking_cycles_started() {
1923 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1924 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1925 "Wrong marking cycle count (started: %d, completed: %d)",
1926 _old_marking_cycles_started, _old_marking_cycles_completed);
1927
1928 _old_marking_cycles_started++;
1929 }
1930
1931 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
1932 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
1933
1934 // We assume that if concurrent == true, then the caller is a
1935 // concurrent thread that was joined the Suspendible Thread
1936 // Set. If there's ever a cheap way to check this, we should add an
1937 // assert here.
1938
1939 // Given that this method is called at the end of a Full GC or of a
1940 // concurrent cycle, and those can be nested (i.e., a Full GC can
1941 // interrupt a concurrent cycle), the number of full collections
1942 // completed should be either one (in the case where there was no
1943 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1944 // behind the number of full collections started.
1945
1946 // This is the case for the inner caller, i.e. a Full GC.
1947 assert(concurrent ||
1948 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1949 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1950 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1951 "is inconsistent with _old_marking_cycles_completed = %u",
1952 _old_marking_cycles_started, _old_marking_cycles_completed);
1953
1954 // This is the case for the outer caller, i.e. the concurrent cycle.
1955 assert(!concurrent ||
1956 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1957 "for outer caller (concurrent cycle): "
1958 "_old_marking_cycles_started = %u "
1959 "is inconsistent with _old_marking_cycles_completed = %u",
1960 _old_marking_cycles_started, _old_marking_cycles_completed);
1961
1962 _old_marking_cycles_completed += 1;
1963
1964 // We need to clear the "in_progress" flag in the CM thread before
1965 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1966 // is set) so that if a waiter requests another System.gc() it doesn't
1967 // incorrectly see that a marking cycle is still in progress.
1968 if (concurrent) {
1969 _cm_thread->set_idle();
1970 }
1971
1972 // This notify_all() will ensure that a thread that called
1973 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
1974 // and it's waiting for a full GC to finish will be woken up. It is
1975 // waiting in VM_G1CollectForAllocation::doit_epilogue().
1976 FullGCCount_lock->notify_all();
1977 }
1978
1979 void G1CollectedHeap::collect(GCCause::Cause cause) {
1980 assert_heap_not_locked();
1981
1982 uint gc_count_before;
1983 uint old_marking_count_before;
1984 uint full_gc_count_before;
1985 bool retry_gc;
1986
1987 do {
1988 retry_gc = false;
1989
1990 {
1991 MutexLocker ml(Heap_lock);
1992
1993 // Read the GC count while holding the Heap_lock
1994 gc_count_before = total_collections();
1995 full_gc_count_before = total_full_collections();
1996 old_marking_count_before = _old_marking_cycles_started;
1997 }
1998
1999 if (should_do_concurrent_full_gc(cause)) {
2000 // Schedule an initial-mark evacuation pause that will start a
2001 // concurrent cycle. We're setting word_size to 0 which means that
2002 // we are not requesting a post-GC allocation.
2003 VM_G1CollectForAllocation op(0, /* word_size */
2004 gc_count_before,
2005 cause,
2006 true, /* should_initiate_conc_mark */
2007 g1_policy()->max_pause_time_ms());
2008 VMThread::execute(&op);
2009 if (!op.pause_succeeded()) {
2010 if (old_marking_count_before == _old_marking_cycles_started) {
2011 retry_gc = op.should_retry_gc();
2012 } else {
2013 // A Full GC happened while we were trying to schedule the
2014 // initial-mark GC. No point in starting a new cycle given
2015 // that the whole heap was collected anyway.
2016 }
2017
2018 if (retry_gc) {
2019 if (GCLocker::is_active_and_needs_gc()) {
2020 GCLocker::stall_until_clear();
2021 }
2022 }
2023 }
2024 } else {
2025 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2026 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2027
2028 // Schedule a standard evacuation pause. We're setting word_size
2029 // to 0 which means that we are not requesting a post-GC allocation.
2030 VM_G1CollectForAllocation op(0, /* word_size */
2031 gc_count_before,
2032 cause,
2033 false, /* should_initiate_conc_mark */
2034 g1_policy()->max_pause_time_ms());
2035 VMThread::execute(&op);
2036 } else {
2037 // Schedule a Full GC.
2038 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2039 VMThread::execute(&op);
2040 }
2041 }
2042 } while (retry_gc);
2043 }
2044
2045 bool G1CollectedHeap::is_in(const void* p) const {
2046 if (_hrm.reserved().contains(p)) {
2047 // Given that we know that p is in the reserved space,
2048 // heap_region_containing() should successfully
2049 // return the containing region.
2050 HeapRegion* hr = heap_region_containing(p);
2051 return hr->is_in(p);
2052 } else {
2053 return false;
2054 }
2055 }
2056
2057 #ifdef ASSERT
2058 bool G1CollectedHeap::is_in_exact(const void* p) const {
2059 bool contains = reserved_region().contains(p);
2060 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2061 if (contains && available) {
2062 return true;
2063 } else {
2064 return false;
2065 }
2066 }
2067 #endif
2068
2069 // Iteration functions.
2070
2071 // Iterates an ObjectClosure over all objects within a HeapRegion.
2072
2073 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2074 ObjectClosure* _cl;
2075 public:
2076 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2077 bool do_heap_region(HeapRegion* r) {
2078 if (!r->is_continues_humongous()) {
2079 r->object_iterate(_cl);
2080 }
2081 return false;
2082 }
2083 };
2084
2085 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2086 IterateObjectClosureRegionClosure blk(cl);
2087 heap_region_iterate(&blk);
2088 }
2089
2090 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2091 _hrm.iterate(cl);
2092 }
2093
2094 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2095 HeapRegionClaimer *hrclaimer,
2096 uint worker_id) const {
2097 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2098 }
2099
2100 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2101 HeapRegionClaimer *hrclaimer) const {
2102 _hrm.par_iterate(cl, hrclaimer, 0);
2103 }
2104
2105 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2106 _collection_set.iterate(cl);
2107 }
2108
2109 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2110 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2111 }
2112
2113 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2114 HeapRegion* hr = heap_region_containing(addr);
2115 return hr->block_start(addr);
2116 }
2117
2118 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2119 HeapRegion* hr = heap_region_containing(addr);
2120 return hr->block_size(addr);
2121 }
2122
2123 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2124 HeapRegion* hr = heap_region_containing(addr);
2125 return hr->block_is_obj(addr);
2126 }
2127
2128 bool G1CollectedHeap::supports_tlab_allocation() const {
2129 return true;
2130 }
2131
2132 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2133 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2134 }
2135
2136 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2137 return _eden.length() * HeapRegion::GrainBytes;
2138 }
2139
2140 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2141 // must be equal to the humongous object limit.
2142 size_t G1CollectedHeap::max_tlab_size() const {
2143 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2144 }
2145
2146 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2147 return _allocator->unsafe_max_tlab_alloc();
2148 }
2149
2150 size_t G1CollectedHeap::max_capacity() const {
2151 return _hrm.reserved().byte_size();
2152 }
2153
2154 jlong G1CollectedHeap::millis_since_last_gc() {
2155 // See the notes in GenCollectedHeap::millis_since_last_gc()
2156 // for more information about the implementation.
2157 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2158 _g1_policy->collection_pause_end_millis();
2159 if (ret_val < 0) {
2160 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2161 ". returning zero instead.", ret_val);
2162 return 0;
2163 }
2164 return ret_val;
2165 }
2166
2167 void G1CollectedHeap::deduplicate_string(oop str) {
2168 assert(java_lang_String::is_instance(str), "invariant");
2169
2170 if (G1StringDedup::is_enabled()) {
2171 G1StringDedup::deduplicate(str);
2172 }
2173 }
2174
2175 void G1CollectedHeap::prepare_for_verify() {
2176 _verifier->prepare_for_verify();
2177 }
2178
2179 void G1CollectedHeap::verify(VerifyOption vo) {
2180 _verifier->verify(vo);
2181 }
2182
2183 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2184 return true;
2185 }
2186
2187 const char* const* G1CollectedHeap::concurrent_phases() const {
2188 return _cm_thread->concurrent_phases();
2189 }
2190
2191 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2192 return _cm_thread->request_concurrent_phase(phase);
2193 }
2194
2195 class PrintRegionClosure: public HeapRegionClosure {
2196 outputStream* _st;
2197 public:
2198 PrintRegionClosure(outputStream* st) : _st(st) {}
2199 bool do_heap_region(HeapRegion* r) {
2200 r->print_on(_st);
2201 return false;
2202 }
2203 };
2204
2205 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2206 const HeapRegion* hr,
2207 const VerifyOption vo) const {
2208 switch (vo) {
2209 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2210 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2211 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2212 default: ShouldNotReachHere();
2213 }
2214 return false; // keep some compilers happy
2215 }
2216
2217 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2218 const VerifyOption vo) const {
2219 switch (vo) {
2220 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2221 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2222 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2223 default: ShouldNotReachHere();
2224 }
2225 return false; // keep some compilers happy
2226 }
2227
2228 void G1CollectedHeap::print_heap_regions() const {
2229 LogTarget(Trace, gc, heap, region) lt;
2230 if (lt.is_enabled()) {
2231 LogStream ls(lt);
2232 print_regions_on(&ls);
2233 }
2234 }
2235
2236 void G1CollectedHeap::print_on(outputStream* st) const {
2237 st->print(" %-20s", "garbage-first heap");
2238 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2239 capacity()/K, used_unlocked()/K);
2240 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2241 p2i(_hrm.reserved().start()),
2242 p2i(_hrm.reserved().end()));
2243 st->cr();
2244 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2245 uint young_regions = young_regions_count();
2246 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2247 (size_t) young_regions * HeapRegion::GrainBytes / K);
2248 uint survivor_regions = survivor_regions_count();
2249 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2250 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2251 st->cr();
2252 MetaspaceUtils::print_on(st);
2253 }
2254
2255 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2256 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2257 "HS=humongous(starts), HC=humongous(continues), "
2258 "CS=collection set, F=free, A=archive, "
2259 "TAMS=top-at-mark-start (previous, next)");
2260 PrintRegionClosure blk(st);
2261 heap_region_iterate(&blk);
2262 }
2263
2264 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2265 print_on(st);
2266
2267 // Print the per-region information.
2268 print_regions_on(st);
2269 }
2270
2271 void G1CollectedHeap::print_on_error(outputStream* st) const {
2272 this->CollectedHeap::print_on_error(st);
2273
2274 if (_cm != NULL) {
2275 st->cr();
2276 _cm->print_on_error(st);
2277 }
2278 }
2279
2280 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2281 workers()->print_worker_threads_on(st);
2282 _cm_thread->print_on(st);
2283 st->cr();
2284 _cm->print_worker_threads_on(st);
2285 _cr->print_threads_on(st);
2286 _young_gen_sampling_thread->print_on(st);
2287 if (G1StringDedup::is_enabled()) {
2288 G1StringDedup::print_worker_threads_on(st);
2289 }
2290 }
2291
2292 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2293 workers()->threads_do(tc);
2294 tc->do_thread(_cm_thread);
2295 _cm->threads_do(tc);
2296 _cr->threads_do(tc);
2297 tc->do_thread(_young_gen_sampling_thread);
2298 if (G1StringDedup::is_enabled()) {
2299 G1StringDedup::threads_do(tc);
2300 }
2301 }
2302
2303 void G1CollectedHeap::print_tracing_info() const {
2304 g1_rem_set()->print_summary_info();
2305 concurrent_mark()->print_summary_info();
2306 }
2307
2308 #ifndef PRODUCT
2309 // Helpful for debugging RSet issues.
2310
2311 class PrintRSetsClosure : public HeapRegionClosure {
2312 private:
2313 const char* _msg;
2314 size_t _occupied_sum;
2315
2316 public:
2317 bool do_heap_region(HeapRegion* r) {
2318 HeapRegionRemSet* hrrs = r->rem_set();
2319 size_t occupied = hrrs->occupied();
2320 _occupied_sum += occupied;
2321
2322 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2323 if (occupied == 0) {
2324 tty->print_cr(" RSet is empty");
2325 } else {
2326 hrrs->print();
2327 }
2328 tty->print_cr("----------");
2329 return false;
2330 }
2331
2332 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2333 tty->cr();
2334 tty->print_cr("========================================");
2335 tty->print_cr("%s", msg);
2336 tty->cr();
2337 }
2338
2339 ~PrintRSetsClosure() {
2340 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2341 tty->print_cr("========================================");
2342 tty->cr();
2343 }
2344 };
2345
2346 void G1CollectedHeap::print_cset_rsets() {
2347 PrintRSetsClosure cl("Printing CSet RSets");
2348 collection_set_iterate(&cl);
2349 }
2350
2351 void G1CollectedHeap::print_all_rsets() {
2352 PrintRSetsClosure cl("Printing All RSets");;
2353 heap_region_iterate(&cl);
2354 }
2355 #endif // PRODUCT
2356
2357 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2358
2359 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2360 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2361 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2362
2363 size_t eden_capacity_bytes =
2364 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2365
2366 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2367 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2368 eden_capacity_bytes, survivor_used_bytes, num_regions());
2369 }
2370
2371 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2372 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2373 stats->unused(), stats->used(), stats->region_end_waste(),
2374 stats->regions_filled(), stats->direct_allocated(),
2375 stats->failure_used(), stats->failure_waste());
2376 }
2377
2378 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2379 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2380 gc_tracer->report_gc_heap_summary(when, heap_summary);
2381
2382 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2383 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2384 }
2385
2386 G1CollectedHeap* G1CollectedHeap::heap() {
2387 CollectedHeap* heap = Universe::heap();
2388 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2389 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2390 return (G1CollectedHeap*)heap;
2391 }
2392
2393 void G1CollectedHeap::gc_prologue(bool full) {
2394 // always_do_update_barrier = false;
2395 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2396
2397 // This summary needs to be printed before incrementing total collections.
2398 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2399
2400 // Update common counters.
2401 increment_total_collections(full /* full gc */);
2402 if (full) {
2403 increment_old_marking_cycles_started();
2404 }
2405
2406 // Fill TLAB's and such
2407 double start = os::elapsedTime();
2408 accumulate_statistics_all_tlabs();
2409 ensure_parsability(true);
2410 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2411 }
2412
2413 void G1CollectedHeap::gc_epilogue(bool full) {
2414 // Update common counters.
2415 if (full) {
2416 // Update the number of full collections that have been completed.
2417 increment_old_marking_cycles_completed(false /* concurrent */);
2418 }
2419
2420 // We are at the end of the GC. Total collections has already been increased.
2421 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2422
2423 // FIXME: what is this about?
2424 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2425 // is set.
2426 #if COMPILER2_OR_JVMCI
2427 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2428 #endif
2429 // always_do_update_barrier = true;
2430
2431 double start = os::elapsedTime();
2432 resize_all_tlabs();
2433 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2434
2435 MemoryService::track_memory_usage();
2436 // We have just completed a GC. Update the soft reference
2437 // policy with the new heap occupancy
2438 Universe::update_heap_info_at_gc();
2439 }
2440
2441 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2442 uint gc_count_before,
2443 bool* succeeded,
2444 GCCause::Cause gc_cause) {
2445 assert_heap_not_locked_and_not_at_safepoint();
2446 VM_G1CollectForAllocation op(word_size,
2447 gc_count_before,
2448 gc_cause,
2449 false, /* should_initiate_conc_mark */
2450 g1_policy()->max_pause_time_ms());
2451 VMThread::execute(&op);
2452
2453 HeapWord* result = op.result();
2454 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2455 assert(result == NULL || ret_succeeded,
2456 "the result should be NULL if the VM did not succeed");
2457 *succeeded = ret_succeeded;
2458
2459 assert_heap_not_locked();
2460 return result;
2461 }
2462
2463 void G1CollectedHeap::do_concurrent_mark() {
2464 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2465 if (!_cm_thread->in_progress()) {
2466 _cm_thread->set_started();
2467 CGC_lock->notify();
2468 }
2469 }
2470
2471 size_t G1CollectedHeap::pending_card_num() {
2472 size_t extra_cards = 0;
2473 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2474 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2475 extra_cards += dcq.size();
2476 }
2477 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2478 size_t buffer_size = dcqs.buffer_size();
2479 size_t buffer_num = dcqs.completed_buffers_num();
2480
2481 return buffer_size * buffer_num + extra_cards;
2482 }
2483
2484 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2485 // We don't nominate objects with many remembered set entries, on
2486 // the assumption that such objects are likely still live.
2487 HeapRegionRemSet* rem_set = r->rem_set();
2488
2489 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2490 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2491 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2492 }
2493
2494 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2495 private:
2496 size_t _total_humongous;
2497 size_t _candidate_humongous;
2498
2499 DirtyCardQueue _dcq;
2500
2501 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2502 assert(region->is_starts_humongous(), "Must start a humongous object");
2503
2504 oop obj = oop(region->bottom());
2505
2506 // Dead objects cannot be eager reclaim candidates. Due to class
2507 // unloading it is unsafe to query their classes so we return early.
2508 if (g1h->is_obj_dead(obj, region)) {
2509 return false;
2510 }
2511
2512 // If we do not have a complete remembered set for the region, then we can
2513 // not be sure that we have all references to it.
2514 if (!region->rem_set()->is_complete()) {
2515 return false;
2516 }
2517 // Candidate selection must satisfy the following constraints
2518 // while concurrent marking is in progress:
2519 //
2520 // * In order to maintain SATB invariants, an object must not be
2521 // reclaimed if it was allocated before the start of marking and
2522 // has not had its references scanned. Such an object must have
2523 // its references (including type metadata) scanned to ensure no
2524 // live objects are missed by the marking process. Objects
2525 // allocated after the start of concurrent marking don't need to
2526 // be scanned.
2527 //
2528 // * An object must not be reclaimed if it is on the concurrent
2529 // mark stack. Objects allocated after the start of concurrent
2530 // marking are never pushed on the mark stack.
2531 //
2532 // Nominating only objects allocated after the start of concurrent
2533 // marking is sufficient to meet both constraints. This may miss
2534 // some objects that satisfy the constraints, but the marking data
2535 // structures don't support efficiently performing the needed
2536 // additional tests or scrubbing of the mark stack.
2537 //
2538 // However, we presently only nominate is_typeArray() objects.
2539 // A humongous object containing references induces remembered
2540 // set entries on other regions. In order to reclaim such an
2541 // object, those remembered sets would need to be cleaned up.
2542 //
2543 // We also treat is_typeArray() objects specially, allowing them
2544 // to be reclaimed even if allocated before the start of
2545 // concurrent mark. For this we rely on mark stack insertion to
2546 // exclude is_typeArray() objects, preventing reclaiming an object
2547 // that is in the mark stack. We also rely on the metadata for
2548 // such objects to be built-in and so ensured to be kept live.
2549 // Frequent allocation and drop of large binary blobs is an
2550 // important use case for eager reclaim, and this special handling
2551 // may reduce needed headroom.
2552
2553 return obj->is_typeArray() &&
2554 g1h->is_potential_eager_reclaim_candidate(region);
2555 }
2556
2557 public:
2558 RegisterHumongousWithInCSetFastTestClosure()
2559 : _total_humongous(0),
2560 _candidate_humongous(0),
2561 _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2562 }
2563
2564 virtual bool do_heap_region(HeapRegion* r) {
2565 if (!r->is_starts_humongous()) {
2566 return false;
2567 }
2568 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2569
2570 bool is_candidate = humongous_region_is_candidate(g1h, r);
2571 uint rindex = r->hrm_index();
2572 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2573 if (is_candidate) {
2574 _candidate_humongous++;
2575 g1h->register_humongous_region_with_cset(rindex);
2576 // Is_candidate already filters out humongous object with large remembered sets.
2577 // If we have a humongous object with a few remembered sets, we simply flush these
2578 // remembered set entries into the DCQS. That will result in automatic
2579 // re-evaluation of their remembered set entries during the following evacuation
2580 // phase.
2581 if (!r->rem_set()->is_empty()) {
2582 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2583 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2584 G1CardTable* ct = g1h->card_table();
2585 HeapRegionRemSetIterator hrrs(r->rem_set());
2586 size_t card_index;
2587 while (hrrs.has_next(card_index)) {
2588 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2589 // The remembered set might contain references to already freed
2590 // regions. Filter out such entries to avoid failing card table
2591 // verification.
2592 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2593 if (*card_ptr != G1CardTable::dirty_card_val()) {
2594 *card_ptr = G1CardTable::dirty_card_val();
2595 _dcq.enqueue(card_ptr);
2596 }
2597 }
2598 }
2599 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2600 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2601 hrrs.n_yielded(), r->rem_set()->occupied());
2602 // We should only clear the card based remembered set here as we will not
2603 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2604 // (and probably never) we do not enter this path if there are other kind of
2605 // remembered sets for this region.
2606 r->rem_set()->clear_locked(true /* only_cardset */);
2607 // Clear_locked() above sets the state to Empty. However we want to continue
2608 // collecting remembered set entries for humongous regions that were not
2609 // reclaimed.
2610 r->rem_set()->set_state_complete();
2611 }
2612 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2613 }
2614 _total_humongous++;
2615
2616 return false;
2617 }
2618
2619 size_t total_humongous() const { return _total_humongous; }
2620 size_t candidate_humongous() const { return _candidate_humongous; }
2621
2622 void flush_rem_set_entries() { _dcq.flush(); }
2623 };
2624
2625 void G1CollectedHeap::register_humongous_regions_with_cset() {
2626 if (!G1EagerReclaimHumongousObjects) {
2627 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2628 return;
2629 }
2630 double time = os::elapsed_counter();
2631
2632 // Collect reclaim candidate information and register candidates with cset.
2633 RegisterHumongousWithInCSetFastTestClosure cl;
2634 heap_region_iterate(&cl);
2635
2636 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2637 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2638 cl.total_humongous(),
2639 cl.candidate_humongous());
2640 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2641
2642 // Finally flush all remembered set entries to re-check into the global DCQS.
2643 cl.flush_rem_set_entries();
2644 }
2645
2646 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2647 public:
2648 bool do_heap_region(HeapRegion* hr) {
2649 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2650 hr->verify_rem_set();
2651 }
2652 return false;
2653 }
2654 };
2655
2656 uint G1CollectedHeap::num_task_queues() const {
2657 return _task_queues->size();
2658 }
2659
2660 #if TASKQUEUE_STATS
2661 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2662 st->print_raw_cr("GC Task Stats");
2663 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2664 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2665 }
2666
2667 void G1CollectedHeap::print_taskqueue_stats() const {
2668 if (!log_is_enabled(Trace, gc, task, stats)) {
2669 return;
2670 }
2671 Log(gc, task, stats) log;
2672 ResourceMark rm;
2673 LogStream ls(log.trace());
2674 outputStream* st = &ls;
2675
2676 print_taskqueue_stats_hdr(st);
2677
2678 TaskQueueStats totals;
2679 const uint n = num_task_queues();
2680 for (uint i = 0; i < n; ++i) {
2681 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2682 totals += task_queue(i)->stats;
2683 }
2684 st->print_raw("tot "); totals.print(st); st->cr();
2685
2686 DEBUG_ONLY(totals.verify());
2687 }
2688
2689 void G1CollectedHeap::reset_taskqueue_stats() {
2690 const uint n = num_task_queues();
2691 for (uint i = 0; i < n; ++i) {
2692 task_queue(i)->stats.reset();
2693 }
2694 }
2695 #endif // TASKQUEUE_STATS
2696
2697 void G1CollectedHeap::wait_for_root_region_scanning() {
2698 double scan_wait_start = os::elapsedTime();
2699 // We have to wait until the CM threads finish scanning the
2700 // root regions as it's the only way to ensure that all the
2701 // objects on them have been correctly scanned before we start
2702 // moving them during the GC.
2703 bool waited = _cm->root_regions()->wait_until_scan_finished();
2704 double wait_time_ms = 0.0;
2705 if (waited) {
2706 double scan_wait_end = os::elapsedTime();
2707 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2708 }
2709 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2710 }
2711
2712 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2713 private:
2714 G1HRPrinter* _hr_printer;
2715 public:
2716 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2717
2718 virtual bool do_heap_region(HeapRegion* r) {
2719 _hr_printer->cset(r);
2720 return false;
2721 }
2722 };
2723
2724 void G1CollectedHeap::start_new_collection_set() {
2725 collection_set()->start_incremental_building();
2726
2727 clear_cset_fast_test();
2728
2729 guarantee(_eden.length() == 0, "eden should have been cleared");
2730 g1_policy()->transfer_survivors_to_cset(survivor());
2731 }
2732
2733 bool
2734 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2735 assert_at_safepoint_on_vm_thread();
2736 guarantee(!is_gc_active(), "collection is not reentrant");
2737
2738 if (GCLocker::check_active_before_gc()) {
2739 return false;
2740 }
2741
2742 _gc_timer_stw->register_gc_start();
2743
2744 GCIdMark gc_id_mark;
2745 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2746
2747 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2748 ResourceMark rm;
2749
2750 g1_policy()->note_gc_start();
2751
2752 wait_for_root_region_scanning();
2753
2754 print_heap_before_gc();
2755 print_heap_regions();
2756 trace_heap_before_gc(_gc_tracer_stw);
2757
2758 _verifier->verify_region_sets_optional();
2759 _verifier->verify_dirty_young_regions();
2760
2761 // We should not be doing initial mark unless the conc mark thread is running
2762 if (!_cm_thread->should_terminate()) {
2763 // This call will decide whether this pause is an initial-mark
2764 // pause. If it is, in_initial_mark_gc() will return true
2765 // for the duration of this pause.
2766 g1_policy()->decide_on_conc_mark_initiation();
2767 }
2768
2769 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2770 assert(!collector_state()->in_initial_mark_gc() ||
2771 collector_state()->in_young_only_phase(), "sanity");
2772
2773 // We also do not allow mixed GCs during marking.
2774 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2775
2776 // Record whether this pause is an initial mark. When the current
2777 // thread has completed its logging output and it's safe to signal
2778 // the CM thread, the flag's value in the policy has been reset.
2779 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2780
2781 // Inner scope for scope based logging, timers, and stats collection
2782 {
2783 EvacuationInfo evacuation_info;
2784
2785 if (collector_state()->in_initial_mark_gc()) {
2786 // We are about to start a marking cycle, so we increment the
2787 // full collection counter.
2788 increment_old_marking_cycles_started();
2789 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2790 }
2791
2792 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2793
2794 GCTraceCPUTime tcpu;
2795
2796 G1HeapVerifier::G1VerifyType verify_type;
2797 FormatBuffer<> gc_string("Pause ");
2798 if (collector_state()->in_initial_mark_gc()) {
2799 gc_string.append("Initial Mark");
2800 verify_type = G1HeapVerifier::G1VerifyInitialMark;
2801 } else if (collector_state()->in_young_only_phase()) {
2802 gc_string.append("Young");
2803 verify_type = G1HeapVerifier::G1VerifyYoungOnly;
2804 } else {
2805 gc_string.append("Mixed");
2806 verify_type = G1HeapVerifier::G1VerifyMixed;
2807 }
2808 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2809
2810 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2811 workers()->active_workers(),
2812 Threads::number_of_non_daemon_threads());
2813 active_workers = workers()->update_active_workers(active_workers);
2814 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2815
2816 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2817 TraceMemoryManagerStats tms(&_memory_manager, gc_cause());
2818
2819 G1HeapTransition heap_transition(this);
2820 size_t heap_used_bytes_before_gc = used();
2821
2822 // Don't dynamically change the number of GC threads this early. A value of
2823 // 0 is used to indicate serial work. When parallel work is done,
2824 // it will be set.
2825
2826 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2827 IsGCActiveMark x;
2828
2829 gc_prologue(false);
2830
2831 if (VerifyRememberedSets) {
2832 log_info(gc, verify)("[Verifying RemSets before GC]");
2833 VerifyRegionRemSetClosure v_cl;
2834 heap_region_iterate(&v_cl);
2835 }
2836
2837 _verifier->verify_before_gc(verify_type);
2838
2839 _verifier->check_bitmaps("GC Start");
2840
2841 #if COMPILER2_OR_JVMCI
2842 DerivedPointerTable::clear();
2843 #endif
2844
2845 // Please see comment in g1CollectedHeap.hpp and
2846 // G1CollectedHeap::ref_processing_init() to see how
2847 // reference processing currently works in G1.
2848
2849 // Enable discovery in the STW reference processor
2850 _ref_processor_stw->enable_discovery();
2851
2852 {
2853 // We want to temporarily turn off discovery by the
2854 // CM ref processor, if necessary, and turn it back on
2855 // on again later if we do. Using a scoped
2856 // NoRefDiscovery object will do this.
2857 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
2858
2859 // Forget the current alloc region (we might even choose it to be part
2860 // of the collection set!).
2861 _allocator->release_mutator_alloc_region();
2862
2863 // This timing is only used by the ergonomics to handle our pause target.
2864 // It is unclear why this should not include the full pause. We will
2865 // investigate this in CR 7178365.
2866 //
2867 // Preserving the old comment here if that helps the investigation:
2868 //
2869 // The elapsed time induced by the start time below deliberately elides
2870 // the possible verification above.
2871 double sample_start_time_sec = os::elapsedTime();
2872
2873 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2874
2875 if (collector_state()->in_initial_mark_gc()) {
2876 concurrent_mark()->pre_initial_mark();
2877 }
2878
2879 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2880
2881 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2882
2883 // Make sure the remembered sets are up to date. This needs to be
2884 // done before register_humongous_regions_with_cset(), because the
2885 // remembered sets are used there to choose eager reclaim candidates.
2886 // If the remembered sets are not up to date we might miss some
2887 // entries that need to be handled.
2888 g1_rem_set()->cleanupHRRS();
2889
2890 register_humongous_regions_with_cset();
2891
2892 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2893
2894 // We call this after finalize_cset() to
2895 // ensure that the CSet has been finalized.
2896 _cm->verify_no_cset_oops();
2897
2898 if (_hr_printer.is_active()) {
2899 G1PrintCollectionSetClosure cl(&_hr_printer);
2900 _collection_set.iterate(&cl);
2901 }
2902
2903 // Initialize the GC alloc regions.
2904 _allocator->init_gc_alloc_regions(evacuation_info);
2905
2906 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
2907 pre_evacuate_collection_set();
2908
2909 // Actually do the work...
2910 evacuate_collection_set(&per_thread_states);
2911
2912 post_evacuate_collection_set(evacuation_info, &per_thread_states);
2913
2914 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
2915 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
2916
2917 eagerly_reclaim_humongous_regions();
2918
2919 record_obj_copy_mem_stats();
2920 _survivor_evac_stats.adjust_desired_plab_sz();
2921 _old_evac_stats.adjust_desired_plab_sz();
2922
2923 double start = os::elapsedTime();
2924 start_new_collection_set();
2925 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2926
2927 if (evacuation_failed()) {
2928 set_used(recalculate_used());
2929 if (_archive_allocator != NULL) {
2930 _archive_allocator->clear_used();
2931 }
2932 for (uint i = 0; i < ParallelGCThreads; i++) {
2933 if (_evacuation_failed_info_array[i].has_failed()) {
2934 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
2935 }
2936 }
2937 } else {
2938 // The "used" of the the collection set have already been subtracted
2939 // when they were freed. Add in the bytes evacuated.
2940 increase_used(g1_policy()->bytes_copied_during_gc());
2941 }
2942
2943 if (collector_state()->in_initial_mark_gc()) {
2944 // We have to do this before we notify the CM threads that
2945 // they can start working to make sure that all the
2946 // appropriate initialization is done on the CM object.
2947 concurrent_mark()->post_initial_mark();
2948 // Note that we don't actually trigger the CM thread at
2949 // this point. We do that later when we're sure that
2950 // the current thread has completed its logging output.
2951 }
2952
2953 allocate_dummy_regions();
2954
2955 _allocator->init_mutator_alloc_region();
2956
2957 {
2958 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2959 if (expand_bytes > 0) {
2960 size_t bytes_before = capacity();
2961 // No need for an ergo logging here,
2962 // expansion_amount() does this when it returns a value > 0.
2963 double expand_ms;
2964 if (!expand(expand_bytes, _workers, &expand_ms)) {
2965 // We failed to expand the heap. Cannot do anything about it.
2966 }
2967 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
2968 }
2969 }
2970
2971 // We redo the verification but now wrt to the new CSet which
2972 // has just got initialized after the previous CSet was freed.
2973 _cm->verify_no_cset_oops();
2974
2975 // This timing is only used by the ergonomics to handle our pause target.
2976 // It is unclear why this should not include the full pause. We will
2977 // investigate this in CR 7178365.
2978 double sample_end_time_sec = os::elapsedTime();
2979 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
2980 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
2981 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
2982
2983 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
2984 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
2985
2986 if (VerifyRememberedSets) {
2987 log_info(gc, verify)("[Verifying RemSets after GC]");
2988 VerifyRegionRemSetClosure v_cl;
2989 heap_region_iterate(&v_cl);
2990 }
2991
2992 _verifier->verify_after_gc(verify_type);
2993 _verifier->check_bitmaps("GC End");
2994
2995 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
2996 _ref_processor_stw->verify_no_references_recorded();
2997
2998 // CM reference discovery will be re-enabled if necessary.
2999 }
3000
3001 #ifdef TRACESPINNING
3002 ParallelTaskTerminator::print_termination_counts();
3003 #endif
3004
3005 gc_epilogue(false);
3006 }
3007
3008 // Print the remainder of the GC log output.
3009 if (evacuation_failed()) {
3010 log_info(gc)("To-space exhausted");
3011 }
3012
3013 g1_policy()->print_phases();
3014 heap_transition.print();
3015
3016 // It is not yet to safe to tell the concurrent mark to
3017 // start as we have some optional output below. We don't want the
3018 // output from the concurrent mark thread interfering with this
3019 // logging output either.
3020
3021 _hrm.verify_optional();
3022 _verifier->verify_region_sets_optional();
3023
3024 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3025 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3026
3027 print_heap_after_gc();
3028 print_heap_regions();
3029 trace_heap_after_gc(_gc_tracer_stw);
3030
3031 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3032 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3033 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3034 // before any GC notifications are raised.
3035 g1mm()->update_sizes();
3036
3037 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3038 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3039 _gc_timer_stw->register_gc_end();
3040 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3041 }
3042 // It should now be safe to tell the concurrent mark thread to start
3043 // without its logging output interfering with the logging output
3044 // that came from the pause.
3045
3046 if (should_start_conc_mark) {
3047 // CAUTION: after the doConcurrentMark() call below,
3048 // the concurrent marking thread(s) could be running
3049 // concurrently with us. Make sure that anything after
3050 // this point does not assume that we are the only GC thread
3051 // running. Note: of course, the actual marking work will
3052 // not start until the safepoint itself is released in
3053 // SuspendibleThreadSet::desynchronize().
3054 do_concurrent_mark();
3055 }
3056
3057 return true;
3058 }
3059
3060 void G1CollectedHeap::remove_self_forwarding_pointers() {
3061 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3062 workers()->run_task(&rsfp_task);
3063 }
3064
3065 void G1CollectedHeap::restore_after_evac_failure() {
3066 double remove_self_forwards_start = os::elapsedTime();
3067
3068 remove_self_forwarding_pointers();
3069 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3070 _preserved_marks_set.restore(&task_executor);
3071
3072 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3073 }
3074
3075 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3076 if (!_evacuation_failed) {
3077 _evacuation_failed = true;
3078 }
3079
3080 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3081 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3082 }
3083
3084 bool G1ParEvacuateFollowersClosure::offer_termination() {
3085 G1ParScanThreadState* const pss = par_scan_state();
3086 start_term_time();
3087 const bool res = terminator()->offer_termination();
3088 end_term_time();
3089 return res;
3090 }
3091
3092 void G1ParEvacuateFollowersClosure::do_void() {
3093 G1ParScanThreadState* const pss = par_scan_state();
3094 pss->trim_queue();
3095 do {
3096 pss->steal_and_trim_queue(queues());
3097 } while (!offer_termination());
3098 }
3099
3100 class G1ParTask : public AbstractGangTask {
3101 protected:
3102 G1CollectedHeap* _g1h;
3103 G1ParScanThreadStateSet* _pss;
3104 RefToScanQueueSet* _queues;
3105 G1RootProcessor* _root_processor;
3106 ParallelTaskTerminator _terminator;
3107 uint _n_workers;
3108
3109 public:
3110 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3111 : AbstractGangTask("G1 collection"),
3112 _g1h(g1h),
3113 _pss(per_thread_states),
3114 _queues(task_queues),
3115 _root_processor(root_processor),
3116 _terminator(n_workers, _queues),
3117 _n_workers(n_workers)
3118 {}
3119
3120 void work(uint worker_id) {
3121 if (worker_id >= _n_workers) return; // no work needed this round
3122
3123 double start_sec = os::elapsedTime();
3124 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3125
3126 {
3127 ResourceMark rm;
3128 HandleMark hm;
3129
3130 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3131
3132 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3133 pss->set_ref_discoverer(rp);
3134
3135 double start_strong_roots_sec = os::elapsedTime();
3136
3137 _root_processor->evacuate_roots(pss, worker_id);
3138
3139 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3140 // treating the nmethods visited to act as roots for concurrent marking.
3141 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3142 // objects copied by the current evacuation.
3143 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id);
3144
3145 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3146
3147 double term_sec = 0.0;
3148 size_t evac_term_attempts = 0;
3149 {
3150 double start = os::elapsedTime();
3151 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3152 evac.do_void();
3153
3154 evac_term_attempts = evac.term_attempts();
3155 term_sec = evac.term_time();
3156 double elapsed_sec = os::elapsedTime() - start;
3157
3158 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3159 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3160 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3161 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3162 }
3163
3164 assert(pss->queue_is_empty(), "should be empty");
3165
3166 if (log_is_enabled(Debug, gc, task, stats)) {
3167 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3168 size_t lab_waste;
3169 size_t lab_undo_waste;
3170 pss->waste(lab_waste, lab_undo_waste);
3171 _g1h->print_termination_stats(worker_id,
3172 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3173 strong_roots_sec * 1000.0, /* strong roots time */
3174 term_sec * 1000.0, /* evac term time */
3175 evac_term_attempts, /* evac term attempts */
3176 lab_waste, /* alloc buffer waste */
3177 lab_undo_waste /* undo waste */
3178 );
3179 }
3180
3181 // Close the inner scope so that the ResourceMark and HandleMark
3182 // destructors are executed here and are included as part of the
3183 // "GC Worker Time".
3184 }
3185 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3186 }
3187 };
3188
3189 void G1CollectedHeap::print_termination_stats_hdr() {
3190 log_debug(gc, task, stats)("GC Termination Stats");
3191 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3192 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3193 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3194 }
3195
3196 void G1CollectedHeap::print_termination_stats(uint worker_id,
3197 double elapsed_ms,
3198 double strong_roots_ms,
3199 double term_ms,
3200 size_t term_attempts,
3201 size_t alloc_buffer_waste,
3202 size_t undo_waste) const {
3203 log_debug(gc, task, stats)
3204 ("%3d %9.2f %9.2f %6.2f "
3205 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3206 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3207 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3208 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3209 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3210 alloc_buffer_waste * HeapWordSize / K,
3211 undo_waste * HeapWordSize / K);
3212 }
3213
3214 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3215 private:
3216 BoolObjectClosure* _is_alive;
3217 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3218
3219 int _initial_string_table_size;
3220 int _initial_symbol_table_size;
3221
3222 bool _process_strings;
3223 int _strings_processed;
3224 int _strings_removed;
3225
3226 bool _process_symbols;
3227 int _symbols_processed;
3228 int _symbols_removed;
3229
3230 bool _process_string_dedup;
3231
3232 public:
3233 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3234 AbstractGangTask("String/Symbol Unlinking"),
3235 _is_alive(is_alive),
3236 _dedup_closure(is_alive, NULL, false),
3237 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3238 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3239 _process_string_dedup(process_string_dedup) {
3240
3241 _initial_string_table_size = StringTable::the_table()->table_size();
3242 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3243 if (process_strings) {
3244 StringTable::clear_parallel_claimed_index();
3245 }
3246 if (process_symbols) {
3247 SymbolTable::clear_parallel_claimed_index();
3248 }
3249 }
3250
3251 ~G1StringAndSymbolCleaningTask() {
3252 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3253 "claim value %d after unlink less than initial string table size %d",
3254 StringTable::parallel_claimed_index(), _initial_string_table_size);
3255 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3256 "claim value %d after unlink less than initial symbol table size %d",
3257 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3258
3259 log_info(gc, stringtable)(
3260 "Cleaned string and symbol table, "
3261 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3262 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3263 strings_processed(), strings_removed(),
3264 symbols_processed(), symbols_removed());
3265 }
3266
3267 void work(uint worker_id) {
3268 int strings_processed = 0;
3269 int strings_removed = 0;
3270 int symbols_processed = 0;
3271 int symbols_removed = 0;
3272 if (_process_strings) {
3273 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3274 Atomic::add(strings_processed, &_strings_processed);
3275 Atomic::add(strings_removed, &_strings_removed);
3276 }
3277 if (_process_symbols) {
3278 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3279 Atomic::add(symbols_processed, &_symbols_processed);
3280 Atomic::add(symbols_removed, &_symbols_removed);
3281 }
3282 if (_process_string_dedup) {
3283 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3284 }
3285 }
3286
3287 size_t strings_processed() const { return (size_t)_strings_processed; }
3288 size_t strings_removed() const { return (size_t)_strings_removed; }
3289
3290 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3291 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3292 };
3293
3294 class G1CodeCacheUnloadingTask {
3295 private:
3296 static Monitor* _lock;
3297
3298 BoolObjectClosure* const _is_alive;
3299 const bool _unloading_occurred;
3300 const uint _num_workers;
3301
3302 // Variables used to claim nmethods.
3303 CompiledMethod* _first_nmethod;
3304 CompiledMethod* volatile _claimed_nmethod;
3305
3306 // The list of nmethods that need to be processed by the second pass.
3307 CompiledMethod* volatile _postponed_list;
3308 volatile uint _num_entered_barrier;
3309
3310 public:
3311 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3312 _is_alive(is_alive),
3313 _unloading_occurred(unloading_occurred),
3314 _num_workers(num_workers),
3315 _first_nmethod(NULL),
3316 _claimed_nmethod(NULL),
3317 _postponed_list(NULL),
3318 _num_entered_barrier(0)
3319 {
3320 CompiledMethod::increase_unloading_clock();
3321 // Get first alive nmethod
3322 CompiledMethodIterator iter = CompiledMethodIterator();
3323 if(iter.next_alive()) {
3324 _first_nmethod = iter.method();
3325 }
3326 _claimed_nmethod = _first_nmethod;
3327 }
3328
3329 ~G1CodeCacheUnloadingTask() {
3330 CodeCache::verify_clean_inline_caches();
3331
3332 CodeCache::set_needs_cache_clean(false);
3333 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3334
3335 CodeCache::verify_icholder_relocations();
3336 }
3337
3338 private:
3339 void add_to_postponed_list(CompiledMethod* nm) {
3340 CompiledMethod* old;
3341 do {
3342 old = _postponed_list;
3343 nm->set_unloading_next(old);
3344 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3345 }
3346
3347 void clean_nmethod(CompiledMethod* nm) {
3348 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3349
3350 if (postponed) {
3351 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3352 add_to_postponed_list(nm);
3353 }
3354
3355 // Mark that this thread has been cleaned/unloaded.
3356 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3357 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3358 }
3359
3360 void clean_nmethod_postponed(CompiledMethod* nm) {
3361 nm->do_unloading_parallel_postponed();
3362 }
3363
3364 static const int MaxClaimNmethods = 16;
3365
3366 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3367 CompiledMethod* first;
3368 CompiledMethodIterator last;
3369
3370 do {
3371 *num_claimed_nmethods = 0;
3372
3373 first = _claimed_nmethod;
3374 last = CompiledMethodIterator(first);
3375
3376 if (first != NULL) {
3377
3378 for (int i = 0; i < MaxClaimNmethods; i++) {
3379 if (!last.next_alive()) {
3380 break;
3381 }
3382 claimed_nmethods[i] = last.method();
3383 (*num_claimed_nmethods)++;
3384 }
3385 }
3386
3387 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3388 }
3389
3390 CompiledMethod* claim_postponed_nmethod() {
3391 CompiledMethod* claim;
3392 CompiledMethod* next;
3393
3394 do {
3395 claim = _postponed_list;
3396 if (claim == NULL) {
3397 return NULL;
3398 }
3399
3400 next = claim->unloading_next();
3401
3402 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3403
3404 return claim;
3405 }
3406
3407 public:
3408 // Mark that we're done with the first pass of nmethod cleaning.
3409 void barrier_mark(uint worker_id) {
3410 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3411 _num_entered_barrier++;
3412 if (_num_entered_barrier == _num_workers) {
3413 ml.notify_all();
3414 }
3415 }
3416
3417 // See if we have to wait for the other workers to
3418 // finish their first-pass nmethod cleaning work.
3419 void barrier_wait(uint worker_id) {
3420 if (_num_entered_barrier < _num_workers) {
3421 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3422 while (_num_entered_barrier < _num_workers) {
3423 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3424 }
3425 }
3426 }
3427
3428 // Cleaning and unloading of nmethods. Some work has to be postponed
3429 // to the second pass, when we know which nmethods survive.
3430 void work_first_pass(uint worker_id) {
3431 // The first nmethods is claimed by the first worker.
3432 if (worker_id == 0 && _first_nmethod != NULL) {
3433 clean_nmethod(_first_nmethod);
3434 _first_nmethod = NULL;
3435 }
3436
3437 int num_claimed_nmethods;
3438 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3439
3440 while (true) {
3441 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3442
3443 if (num_claimed_nmethods == 0) {
3444 break;
3445 }
3446
3447 for (int i = 0; i < num_claimed_nmethods; i++) {
3448 clean_nmethod(claimed_nmethods[i]);
3449 }
3450 }
3451 }
3452
3453 void work_second_pass(uint worker_id) {
3454 CompiledMethod* nm;
3455 // Take care of postponed nmethods.
3456 while ((nm = claim_postponed_nmethod()) != NULL) {
3457 clean_nmethod_postponed(nm);
3458 }
3459 }
3460 };
3461
3462 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3463
3464 class G1KlassCleaningTask : public StackObj {
3465 volatile int _clean_klass_tree_claimed;
3466 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3467
3468 public:
3469 G1KlassCleaningTask() :
3470 _clean_klass_tree_claimed(0),
3471 _klass_iterator() {
3472 }
3473
3474 private:
3475 bool claim_clean_klass_tree_task() {
3476 if (_clean_klass_tree_claimed) {
3477 return false;
3478 }
3479
3480 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3481 }
3482
3483 InstanceKlass* claim_next_klass() {
3484 Klass* klass;
3485 do {
3486 klass =_klass_iterator.next_klass();
3487 } while (klass != NULL && !klass->is_instance_klass());
3488
3489 // this can be null so don't call InstanceKlass::cast
3490 return static_cast<InstanceKlass*>(klass);
3491 }
3492
3493 public:
3494
3495 void clean_klass(InstanceKlass* ik) {
3496 ik->clean_weak_instanceklass_links();
3497 }
3498
3499 void work() {
3500 ResourceMark rm;
3501
3502 // One worker will clean the subklass/sibling klass tree.
3503 if (claim_clean_klass_tree_task()) {
3504 Klass::clean_subklass_tree();
3505 }
3506
3507 // All workers will help cleaning the classes,
3508 InstanceKlass* klass;
3509 while ((klass = claim_next_klass()) != NULL) {
3510 clean_klass(klass);
3511 }
3512 }
3513 };
3514
3515 class G1ResolvedMethodCleaningTask : public StackObj {
3516 volatile int _resolved_method_task_claimed;
3517 public:
3518 G1ResolvedMethodCleaningTask() :
3519 _resolved_method_task_claimed(0) {}
3520
3521 bool claim_resolved_method_task() {
3522 if (_resolved_method_task_claimed) {
3523 return false;
3524 }
3525 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3526 }
3527
3528 // These aren't big, one thread can do it all.
3529 void work() {
3530 if (claim_resolved_method_task()) {
3531 ResolvedMethodTable::unlink();
3532 }
3533 }
3534 };
3535
3536
3537 // To minimize the remark pause times, the tasks below are done in parallel.
3538 class G1ParallelCleaningTask : public AbstractGangTask {
3539 private:
3540 bool _unloading_occurred;
3541 G1StringAndSymbolCleaningTask _string_symbol_task;
3542 G1CodeCacheUnloadingTask _code_cache_task;
3543 G1KlassCleaningTask _klass_cleaning_task;
3544 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3545
3546 public:
3547 // The constructor is run in the VMThread.
3548 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3549 AbstractGangTask("Parallel Cleaning"),
3550 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3551 _code_cache_task(num_workers, is_alive, unloading_occurred),
3552 _klass_cleaning_task(),
3553 _unloading_occurred(unloading_occurred),
3554 _resolved_method_cleaning_task() {
3555 }
3556
3557 // The parallel work done by all worker threads.
3558 void work(uint worker_id) {
3559 // Do first pass of code cache cleaning.
3560 _code_cache_task.work_first_pass(worker_id);
3561
3562 // Let the threads mark that the first pass is done.
3563 _code_cache_task.barrier_mark(worker_id);
3564
3565 // Clean the Strings and Symbols.
3566 _string_symbol_task.work(worker_id);
3567
3568 // Clean unreferenced things in the ResolvedMethodTable
3569 _resolved_method_cleaning_task.work();
3570
3571 // Wait for all workers to finish the first code cache cleaning pass.
3572 _code_cache_task.barrier_wait(worker_id);
3573
3574 // Do the second code cache cleaning work, which realize on
3575 // the liveness information gathered during the first pass.
3576 _code_cache_task.work_second_pass(worker_id);
3577
3578 // Clean all klasses that were not unloaded.
3579 // The weak metadata in klass doesn't need to be
3580 // processed if there was no unloading.
3581 if (_unloading_occurred) {
3582 _klass_cleaning_task.work();
3583 }
3584 }
3585 };
3586
3587
3588 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3589 bool class_unloading_occurred) {
3590 uint n_workers = workers()->active_workers();
3591
3592 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3593 workers()->run_task(&g1_unlink_task);
3594 }
3595
3596 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3597 bool process_strings,
3598 bool process_symbols,
3599 bool process_string_dedup) {
3600 if (!process_strings && !process_symbols && !process_string_dedup) {
3601 // Nothing to clean.
3602 return;
3603 }
3604
3605 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3606 workers()->run_task(&g1_unlink_task);
3607
3608 }
3609
3610 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3611 private:
3612 DirtyCardQueueSet* _queue;
3613 G1CollectedHeap* _g1h;
3614 public:
3615 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3616 _queue(queue), _g1h(g1h) { }
3617
3618 virtual void work(uint worker_id) {
3619 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3620 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3621
3622 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3623 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3624
3625 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3626 }
3627 };
3628
3629 void G1CollectedHeap::redirty_logged_cards() {
3630 double redirty_logged_cards_start = os::elapsedTime();
3631
3632 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3633 dirty_card_queue_set().reset_for_par_iteration();
3634 workers()->run_task(&redirty_task);
3635
3636 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3637 dcq.merge_bufferlists(&dirty_card_queue_set());
3638 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3639
3640 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3641 }
3642
3643 // Weak Reference Processing support
3644
3645 bool G1STWIsAliveClosure::do_object_b(oop p) {
3646 // An object is reachable if it is outside the collection set,
3647 // or is inside and copied.
3648 return !_g1h->is_in_cset(p) || p->is_forwarded();
3649 }
3650
3651 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3652 assert(obj != NULL, "must not be NULL");
3653 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3654 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3655 // may falsely indicate that this is not the case here: however the collection set only
3656 // contains old regions when concurrent mark is not running.
3657 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3658 }
3659
3660 // Non Copying Keep Alive closure
3661 class G1KeepAliveClosure: public OopClosure {
3662 G1CollectedHeap*_g1h;
3663 public:
3664 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3665 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3666 void do_oop(oop* p) {
3667 oop obj = *p;
3668 assert(obj != NULL, "the caller should have filtered out NULL values");
3669
3670 const InCSetState cset_state =_g1h->in_cset_state(obj);
3671 if (!cset_state.is_in_cset_or_humongous()) {
3672 return;
3673 }
3674 if (cset_state.is_in_cset()) {
3675 assert( obj->is_forwarded(), "invariant" );
3676 *p = obj->forwardee();
3677 } else {
3678 assert(!obj->is_forwarded(), "invariant" );
3679 assert(cset_state.is_humongous(),
3680 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3681 _g1h->set_humongous_is_live(obj);
3682 }
3683 }
3684 };
3685
3686 // Copying Keep Alive closure - can be called from both
3687 // serial and parallel code as long as different worker
3688 // threads utilize different G1ParScanThreadState instances
3689 // and different queues.
3690
3691 class G1CopyingKeepAliveClosure: public OopClosure {
3692 G1CollectedHeap* _g1h;
3693 OopClosure* _copy_non_heap_obj_cl;
3694 G1ParScanThreadState* _par_scan_state;
3695
3696 public:
3697 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3698 OopClosure* non_heap_obj_cl,
3699 G1ParScanThreadState* pss):
3700 _g1h(g1h),
3701 _copy_non_heap_obj_cl(non_heap_obj_cl),
3702 _par_scan_state(pss)
3703 {}
3704
3705 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3706 virtual void do_oop( oop* p) { do_oop_work(p); }
3707
3708 template <class T> void do_oop_work(T* p) {
3709 oop obj = RawAccess<>::oop_load(p);
3710
3711 if (_g1h->is_in_cset_or_humongous(obj)) {
3712 // If the referent object has been forwarded (either copied
3713 // to a new location or to itself in the event of an
3714 // evacuation failure) then we need to update the reference
3715 // field and, if both reference and referent are in the G1
3716 // heap, update the RSet for the referent.
3717 //
3718 // If the referent has not been forwarded then we have to keep
3719 // it alive by policy. Therefore we have copy the referent.
3720 //
3721 // If the reference field is in the G1 heap then we can push
3722 // on the PSS queue. When the queue is drained (after each
3723 // phase of reference processing) the object and it's followers
3724 // will be copied, the reference field set to point to the
3725 // new location, and the RSet updated. Otherwise we need to
3726 // use the the non-heap or metadata closures directly to copy
3727 // the referent object and update the pointer, while avoiding
3728 // updating the RSet.
3729
3730 if (_g1h->is_in_g1_reserved(p)) {
3731 _par_scan_state->push_on_queue(p);
3732 } else {
3733 assert(!Metaspace::contains((const void*)p),
3734 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3735 _copy_non_heap_obj_cl->do_oop(p);
3736 }
3737 }
3738 }
3739 };
3740
3741 // Serial drain queue closure. Called as the 'complete_gc'
3742 // closure for each discovered list in some of the
3743 // reference processing phases.
3744
3745 class G1STWDrainQueueClosure: public VoidClosure {
3746 protected:
3747 G1CollectedHeap* _g1h;
3748 G1ParScanThreadState* _par_scan_state;
3749
3750 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3751
3752 public:
3753 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3754 _g1h(g1h),
3755 _par_scan_state(pss)
3756 { }
3757
3758 void do_void() {
3759 G1ParScanThreadState* const pss = par_scan_state();
3760 pss->trim_queue();
3761 }
3762 };
3763
3764 // Parallel Reference Processing closures
3765
3766 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3767 // processing during G1 evacuation pauses.
3768
3769 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3770 private:
3771 G1CollectedHeap* _g1h;
3772 G1ParScanThreadStateSet* _pss;
3773 RefToScanQueueSet* _queues;
3774 WorkGang* _workers;
3775 uint _active_workers;
3776
3777 public:
3778 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3779 G1ParScanThreadStateSet* per_thread_states,
3780 WorkGang* workers,
3781 RefToScanQueueSet *task_queues,
3782 uint n_workers) :
3783 _g1h(g1h),
3784 _pss(per_thread_states),
3785 _queues(task_queues),
3786 _workers(workers),
3787 _active_workers(n_workers)
3788 {
3789 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3790 }
3791
3792 // Executes the given task using concurrent marking worker threads.
3793 virtual void execute(ProcessTask& task);
3794 };
3795
3796 // Gang task for possibly parallel reference processing
3797
3798 class G1STWRefProcTaskProxy: public AbstractGangTask {
3799 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3800 ProcessTask& _proc_task;
3801 G1CollectedHeap* _g1h;
3802 G1ParScanThreadStateSet* _pss;
3803 RefToScanQueueSet* _task_queues;
3804 ParallelTaskTerminator* _terminator;
3805
3806 public:
3807 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3808 G1CollectedHeap* g1h,
3809 G1ParScanThreadStateSet* per_thread_states,
3810 RefToScanQueueSet *task_queues,
3811 ParallelTaskTerminator* terminator) :
3812 AbstractGangTask("Process reference objects in parallel"),
3813 _proc_task(proc_task),
3814 _g1h(g1h),
3815 _pss(per_thread_states),
3816 _task_queues(task_queues),
3817 _terminator(terminator)
3818 {}
3819
3820 virtual void work(uint worker_id) {
3821 // The reference processing task executed by a single worker.
3822 ResourceMark rm;
3823 HandleMark hm;
3824
3825 G1STWIsAliveClosure is_alive(_g1h);
3826
3827 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3828 pss->set_ref_discoverer(NULL);
3829
3830 // Keep alive closure.
3831 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3832
3833 // Complete GC closure
3834 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3835
3836 // Call the reference processing task's work routine.
3837 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3838
3839 // Note we cannot assert that the refs array is empty here as not all
3840 // of the processing tasks (specifically phase2 - pp2_work) execute
3841 // the complete_gc closure (which ordinarily would drain the queue) so
3842 // the queue may not be empty.
3843 }
3844 };
3845
3846 // Driver routine for parallel reference processing.
3847 // Creates an instance of the ref processing gang
3848 // task and has the worker threads execute it.
3849 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
3850 assert(_workers != NULL, "Need parallel worker threads.");
3851
3852 ParallelTaskTerminator terminator(_active_workers, _queues);
3853 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3854
3855 _workers->run_task(&proc_task_proxy);
3856 }
3857
3858 // End of weak reference support closures
3859
3860 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3861 double ref_proc_start = os::elapsedTime();
3862
3863 ReferenceProcessor* rp = _ref_processor_stw;
3864 assert(rp->discovery_enabled(), "should have been enabled");
3865
3866 // Closure to test whether a referent is alive.
3867 G1STWIsAliveClosure is_alive(this);
3868
3869 // Even when parallel reference processing is enabled, the processing
3870 // of JNI refs is serial and performed serially by the current thread
3871 // rather than by a worker. The following PSS will be used for processing
3872 // JNI refs.
3873
3874 // Use only a single queue for this PSS.
3875 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3876 pss->set_ref_discoverer(NULL);
3877 assert(pss->queue_is_empty(), "pre-condition");
3878
3879 // Keep alive closure.
3880 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
3881
3882 // Serial Complete GC closure
3883 G1STWDrainQueueClosure drain_queue(this, pss);
3884
3885 // Setup the soft refs policy...
3886 rp->setup_policy(false);
3887
3888 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
3889
3890 ReferenceProcessorStats stats;
3891 if (!rp->processing_is_mt()) {
3892 // Serial reference processing...
3893 stats = rp->process_discovered_references(&is_alive,
3894 &keep_alive,
3895 &drain_queue,
3896 NULL,
3897 pt);
3898 } else {
3899 uint no_of_gc_workers = workers()->active_workers();
3900
3901 // Parallel reference processing
3902 assert(no_of_gc_workers <= rp->max_num_queues(),
3903 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3904 no_of_gc_workers, rp->max_num_queues());
3905
3906 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
3907 stats = rp->process_discovered_references(&is_alive,
3908 &keep_alive,
3909 &drain_queue,
3910 &par_task_executor,
3911 pt);
3912 }
3913
3914 _gc_tracer_stw->report_gc_reference_stats(stats);
3915
3916 // We have completed copying any necessary live referent objects.
3917 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3918
3919 make_pending_list_reachable();
3920
3921 rp->verify_no_references_recorded();
3922
3923 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3924 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3925 }
3926
3927 void G1CollectedHeap::make_pending_list_reachable() {
3928 if (collector_state()->in_initial_mark_gc()) {
3929 oop pll_head = Universe::reference_pending_list();
3930 if (pll_head != NULL) {
3931 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3932 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3933 }
3934 }
3935 }
3936
3937 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3938 double merge_pss_time_start = os::elapsedTime();
3939 per_thread_states->flush();
3940 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3941 }
3942
3943 void G1CollectedHeap::pre_evacuate_collection_set() {
3944 _expand_heap_after_alloc_failure = true;
3945 _evacuation_failed = false;
3946
3947 // Disable the hot card cache.
3948 _hot_card_cache->reset_hot_cache_claimed_index();
3949 _hot_card_cache->set_use_cache(false);
3950
3951 g1_rem_set()->prepare_for_oops_into_collection_set_do();
3952 _preserved_marks_set.assert_empty();
3953
3954 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3955
3956 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3957 if (collector_state()->in_initial_mark_gc()) {
3958 double start_clear_claimed_marks = os::elapsedTime();
3959
3960 ClassLoaderDataGraph::clear_claimed_marks();
3961
3962 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3963 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3964 }
3965 }
3966
3967 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3968 // Should G1EvacuationFailureALot be in effect for this GC?
3969 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3970
3971 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3972
3973 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3974
3975 double start_par_time_sec = os::elapsedTime();
3976 double end_par_time_sec;
3977
3978 {
3979 const uint n_workers = workers()->active_workers();
3980 G1RootProcessor root_processor(this, n_workers);
3981 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
3982
3983 print_termination_stats_hdr();
3984
3985 workers()->run_task(&g1_par_task);
3986 end_par_time_sec = os::elapsedTime();
3987
3988 // Closing the inner scope will execute the destructor
3989 // for the G1RootProcessor object. We record the current
3990 // elapsed time before closing the scope so that time
3991 // taken for the destructor is NOT included in the
3992 // reported parallel time.
3993 }
3994
3995 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
3996 phase_times->record_par_time(par_time_ms);
3997
3998 double code_root_fixup_time_ms =
3999 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4000 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4001 }
4002
4003 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4004 // Also cleans the card table from temporary duplicate detection information used
4005 // during UpdateRS/ScanRS.
4006 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4007
4008 // Process any discovered reference objects - we have
4009 // to do this _before_ we retire the GC alloc regions
4010 // as we may have to copy some 'reachable' referent
4011 // objects (and their reachable sub-graphs) that were
4012 // not copied during the pause.
4013 process_discovered_references(per_thread_states);
4014
4015 // FIXME
4016 // CM's reference processing also cleans up the string and symbol tables.
4017 // Should we do that here also? We could, but it is a serial operation
4018 // and could significantly increase the pause time.
4019
4020 G1STWIsAliveClosure is_alive(this);
4021 G1KeepAliveClosure keep_alive(this);
4022
4023 {
4024 double start = os::elapsedTime();
4025
4026 WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4027
4028 double time_ms = (os::elapsedTime() - start) * 1000.0;
4029 g1_policy()->phase_times()->record_weak_ref_proc_time(time_ms);
4030 }
4031
4032 if (G1StringDedup::is_enabled()) {
4033 double fixup_start = os::elapsedTime();
4034
4035 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4036
4037 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4038 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4039 }
4040
4041 if (evacuation_failed()) {
4042 restore_after_evac_failure();
4043
4044 // Reset the G1EvacuationFailureALot counters and flags
4045 // Note: the values are reset only when an actual
4046 // evacuation failure occurs.
4047 NOT_PRODUCT(reset_evacuation_should_fail();)
4048 }
4049
4050 _preserved_marks_set.assert_empty();
4051
4052 _allocator->release_gc_alloc_regions(evacuation_info);
4053
4054 merge_per_thread_state_info(per_thread_states);
4055
4056 // Reset and re-enable the hot card cache.
4057 // Note the counts for the cards in the regions in the
4058 // collection set are reset when the collection set is freed.
4059 _hot_card_cache->reset_hot_cache();
4060 _hot_card_cache->set_use_cache(true);
4061
4062 purge_code_root_memory();
4063
4064 redirty_logged_cards();
4065 #if COMPILER2_OR_JVMCI
4066 double start = os::elapsedTime();
4067 DerivedPointerTable::update_pointers();
4068 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4069 #endif
4070 g1_policy()->print_age_table();
4071 }
4072
4073 void G1CollectedHeap::record_obj_copy_mem_stats() {
4074 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4075
4076 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4077 create_g1_evac_summary(&_old_evac_stats));
4078 }
4079
4080 void G1CollectedHeap::free_region(HeapRegion* hr,
4081 FreeRegionList* free_list,
4082 bool skip_remset,
4083 bool skip_hot_card_cache,
4084 bool locked) {
4085 assert(!hr->is_free(), "the region should not be free");
4086 assert(!hr->is_empty(), "the region should not be empty");
4087 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4088 assert(free_list != NULL, "pre-condition");
4089
4090 if (G1VerifyBitmaps) {
4091 MemRegion mr(hr->bottom(), hr->end());
4092 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4093 }
4094
4095 // Clear the card counts for this region.
4096 // Note: we only need to do this if the region is not young
4097 // (since we don't refine cards in young regions).
4098 if (!skip_hot_card_cache && !hr->is_young()) {
4099 _hot_card_cache->reset_card_counts(hr);
4100 }
4101 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4102 _g1_policy->remset_tracker()->update_at_free(hr);
4103 free_list->add_ordered(hr);
4104 }
4105
4106 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4107 FreeRegionList* free_list) {
4108 assert(hr->is_humongous(), "this is only for humongous regions");
4109 assert(free_list != NULL, "pre-condition");
4110 hr->clear_humongous();
4111 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
4112 }
4113
4114 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4115 const uint humongous_regions_removed) {
4116 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4117 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4118 _old_set.bulk_remove(old_regions_removed);
4119 _humongous_set.bulk_remove(humongous_regions_removed);
4120 }
4121
4122 }
4123
4124 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4125 assert(list != NULL, "list can't be null");
4126 if (!list->is_empty()) {
4127 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4128 _hrm.insert_list_into_free_list(list);
4129 }
4130 }
4131
4132 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4133 decrease_used(bytes);
4134 }
4135
4136 class G1FreeCollectionSetTask : public AbstractGangTask {
4137 private:
4138
4139 // Closure applied to all regions in the collection set to do work that needs to
4140 // be done serially in a single thread.
4141 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4142 private:
4143 EvacuationInfo* _evacuation_info;
4144 const size_t* _surviving_young_words;
4145
4146 // Bytes used in successfully evacuated regions before the evacuation.
4147 size_t _before_used_bytes;
4148 // Bytes used in unsucessfully evacuated regions before the evacuation
4149 size_t _after_used_bytes;
4150
4151 size_t _bytes_allocated_in_old_since_last_gc;
4152
4153 size_t _failure_used_words;
4154 size_t _failure_waste_words;
4155
4156 FreeRegionList _local_free_list;
4157 public:
4158 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4159 HeapRegionClosure(),
4160 _evacuation_info(evacuation_info),
4161 _surviving_young_words(surviving_young_words),
4162 _before_used_bytes(0),
4163 _after_used_bytes(0),
4164 _bytes_allocated_in_old_since_last_gc(0),
4165 _failure_used_words(0),
4166 _failure_waste_words(0),
4167 _local_free_list("Local Region List for CSet Freeing") {
4168 }
4169
4170 virtual bool do_heap_region(HeapRegion* r) {
4171 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4172
4173 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4174 g1h->clear_in_cset(r);
4175
4176 if (r->is_young()) {
4177 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4178 "Young index %d is wrong for region %u of type %s with %u young regions",
4179 r->young_index_in_cset(),
4180 r->hrm_index(),
4181 r->get_type_str(),
4182 g1h->collection_set()->young_region_length());
4183 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4184 r->record_surv_words_in_group(words_survived);
4185 }
4186
4187 if (!r->evacuation_failed()) {
4188 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4189 _before_used_bytes += r->used();
4190 g1h->free_region(r,
4191 &_local_free_list,
4192 true, /* skip_remset */
4193 true, /* skip_hot_card_cache */
4194 true /* locked */);
4195 } else {
4196 r->uninstall_surv_rate_group();
4197 r->set_young_index_in_cset(-1);
4198 r->set_evacuation_failed(false);
4199 // When moving a young gen region to old gen, we "allocate" that whole region
4200 // there. This is in addition to any already evacuated objects. Notify the
4201 // policy about that.
4202 // Old gen regions do not cause an additional allocation: both the objects
4203 // still in the region and the ones already moved are accounted for elsewhere.
4204 if (r->is_young()) {
4205 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4206 }
4207 // The region is now considered to be old.
4208 r->set_old();
4209 // Do some allocation statistics accounting. Regions that failed evacuation
4210 // are always made old, so there is no need to update anything in the young
4211 // gen statistics, but we need to update old gen statistics.
4212 size_t used_words = r->marked_bytes() / HeapWordSize;
4213
4214 _failure_used_words += used_words;
4215 _failure_waste_words += HeapRegion::GrainWords - used_words;
4216
4217 g1h->old_set_add(r);
4218 _after_used_bytes += r->used();
4219 }
4220 return false;
4221 }
4222
4223 void complete_work() {
4224 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4225
4226 _evacuation_info->set_regions_freed(_local_free_list.length());
4227 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4228
4229 g1h->prepend_to_freelist(&_local_free_list);
4230 g1h->decrement_summary_bytes(_before_used_bytes);
4231
4232 G1Policy* policy = g1h->g1_policy();
4233 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4234
4235 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4236 }
4237 };
4238
4239 G1CollectionSet* _collection_set;
4240 G1SerialFreeCollectionSetClosure _cl;
4241 const size_t* _surviving_young_words;
4242
4243 size_t _rs_lengths;
4244
4245 volatile jint _serial_work_claim;
4246
4247 struct WorkItem {
4248 uint region_idx;
4249 bool is_young;
4250 bool evacuation_failed;
4251
4252 WorkItem(HeapRegion* r) {
4253 region_idx = r->hrm_index();
4254 is_young = r->is_young();
4255 evacuation_failed = r->evacuation_failed();
4256 }
4257 };
4258
4259 volatile size_t _parallel_work_claim;
4260 size_t _num_work_items;
4261 WorkItem* _work_items;
4262
4263 void do_serial_work() {
4264 // Need to grab the lock to be allowed to modify the old region list.
4265 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4266 _collection_set->iterate(&_cl);
4267 }
4268
4269 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4270 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4271
4272 HeapRegion* r = g1h->region_at(region_idx);
4273 assert(!g1h->is_on_master_free_list(r), "sanity");
4274
4275 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4276
4277 if (!is_young) {
4278 g1h->_hot_card_cache->reset_card_counts(r);
4279 }
4280
4281 if (!evacuation_failed) {
4282 r->rem_set()->clear_locked();
4283 }
4284 }
4285
4286 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4287 private:
4288 size_t _cur_idx;
4289 WorkItem* _work_items;
4290 public:
4291 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4292
4293 virtual bool do_heap_region(HeapRegion* r) {
4294 _work_items[_cur_idx++] = WorkItem(r);
4295 return false;
4296 }
4297 };
4298
4299 void prepare_work() {
4300 G1PrepareFreeCollectionSetClosure cl(_work_items);
4301 _collection_set->iterate(&cl);
4302 }
4303
4304 void complete_work() {
4305 _cl.complete_work();
4306
4307 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4308 policy->record_max_rs_lengths(_rs_lengths);
4309 policy->cset_regions_freed();
4310 }
4311 public:
4312 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4313 AbstractGangTask("G1 Free Collection Set"),
4314 _cl(evacuation_info, surviving_young_words),
4315 _collection_set(collection_set),
4316 _surviving_young_words(surviving_young_words),
4317 _serial_work_claim(0),
4318 _rs_lengths(0),
4319 _parallel_work_claim(0),
4320 _num_work_items(collection_set->region_length()),
4321 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4322 prepare_work();
4323 }
4324
4325 ~G1FreeCollectionSetTask() {
4326 complete_work();
4327 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4328 }
4329
4330 // Chunk size for work distribution. The chosen value has been determined experimentally
4331 // to be a good tradeoff between overhead and achievable parallelism.
4332 static uint chunk_size() { return 32; }
4333
4334 virtual void work(uint worker_id) {
4335 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4336
4337 // Claim serial work.
4338 if (_serial_work_claim == 0) {
4339 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4340 if (value == 0) {
4341 double serial_time = os::elapsedTime();
4342 do_serial_work();
4343 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4344 }
4345 }
4346
4347 // Start parallel work.
4348 double young_time = 0.0;
4349 bool has_young_time = false;
4350 double non_young_time = 0.0;
4351 bool has_non_young_time = false;
4352
4353 while (true) {
4354 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4355 size_t cur = end - chunk_size();
4356
4357 if (cur >= _num_work_items) {
4358 break;
4359 }
4360
4361 double start_time = os::elapsedTime();
4362
4363 end = MIN2(end, _num_work_items);
4364
4365 for (; cur < end; cur++) {
4366 bool is_young = _work_items[cur].is_young;
4367
4368 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4369
4370 double end_time = os::elapsedTime();
4371 double time_taken = end_time - start_time;
4372 if (is_young) {
4373 young_time += time_taken;
4374 has_young_time = true;
4375 } else {
4376 non_young_time += time_taken;
4377 has_non_young_time = true;
4378 }
4379 start_time = end_time;
4380 }
4381 }
4382
4383 if (has_young_time) {
4384 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4385 }
4386 if (has_non_young_time) {
4387 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4388 }
4389 }
4390 };
4391
4392 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4393 _eden.clear();
4394
4395 double free_cset_start_time = os::elapsedTime();
4396
4397 {
4398 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4399 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4400
4401 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4402
4403 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4404 cl.name(),
4405 num_workers,
4406 _collection_set.region_length());
4407 workers()->run_task(&cl, num_workers);
4408 }
4409 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4410
4411 collection_set->clear();
4412 }
4413
4414 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4415 private:
4416 FreeRegionList* _free_region_list;
4417 HeapRegionSet* _proxy_set;
4418 uint _humongous_objects_reclaimed;
4419 uint _humongous_regions_reclaimed;
4420 size_t _freed_bytes;
4421 public:
4422
4423 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4424 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4425 }
4426
4427 virtual bool do_heap_region(HeapRegion* r) {
4428 if (!r->is_starts_humongous()) {
4429 return false;
4430 }
4431
4432 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4433
4434 oop obj = (oop)r->bottom();
4435 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4436
4437 // The following checks whether the humongous object is live are sufficient.
4438 // The main additional check (in addition to having a reference from the roots
4439 // or the young gen) is whether the humongous object has a remembered set entry.
4440 //
4441 // A humongous object cannot be live if there is no remembered set for it
4442 // because:
4443 // - there can be no references from within humongous starts regions referencing
4444 // the object because we never allocate other objects into them.
4445 // (I.e. there are no intra-region references that may be missed by the
4446 // remembered set)
4447 // - as soon there is a remembered set entry to the humongous starts region
4448 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4449 // until the end of a concurrent mark.
4450 //
4451 // It is not required to check whether the object has been found dead by marking
4452 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4453 // all objects allocated during that time are considered live.
4454 // SATB marking is even more conservative than the remembered set.
4455 // So if at this point in the collection there is no remembered set entry,
4456 // nobody has a reference to it.
4457 // At the start of collection we flush all refinement logs, and remembered sets
4458 // are completely up-to-date wrt to references to the humongous object.
4459 //
4460 // Other implementation considerations:
4461 // - never consider object arrays at this time because they would pose
4462 // considerable effort for cleaning up the the remembered sets. This is
4463 // required because stale remembered sets might reference locations that
4464 // are currently allocated into.
4465 uint region_idx = r->hrm_index();
4466 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4467 !r->rem_set()->is_empty()) {
4468 log_debug(gc, humongous)("Live humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
4469 region_idx,
4470 (size_t)obj->size() * HeapWordSize,
4471 p2i(r->bottom()),
4472 r->rem_set()->occupied(),
4473 r->rem_set()->strong_code_roots_list_length(),
4474 next_bitmap->is_marked(r->bottom()),
4475 g1h->is_humongous_reclaim_candidate(region_idx),
4476 obj->is_typeArray()
4477 );
4478 return false;
4479 }
4480
4481 guarantee(obj->is_typeArray(),
4482 "Only eagerly reclaiming type arrays is supported, but the object "
4483 PTR_FORMAT " is not.", p2i(r->bottom()));
4484
4485 log_debug(gc, humongous)("Dead humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
4486 region_idx,
4487 (size_t)obj->size() * HeapWordSize,
4488 p2i(r->bottom()),
4489 r->rem_set()->occupied(),
4490 r->rem_set()->strong_code_roots_list_length(),
4491 next_bitmap->is_marked(r->bottom()),
4492 g1h->is_humongous_reclaim_candidate(region_idx),
4493 obj->is_typeArray()
4494 );
4495
4496 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4497 cm->humongous_object_eagerly_reclaimed(r);
4498 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4499 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4500 region_idx,
4501 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4502 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4503 _humongous_objects_reclaimed++;
4504 do {
4505 HeapRegion* next = g1h->next_region_in_humongous(r);
4506 _freed_bytes += r->used();
4507 r->set_containing_set(NULL);
4508 _humongous_regions_reclaimed++;
4509 g1h->free_humongous_region(r, _free_region_list);
4510 r = next;
4511 } while (r != NULL);
4512
4513 return false;
4514 }
4515
4516 uint humongous_objects_reclaimed() {
4517 return _humongous_objects_reclaimed;
4518 }
4519
4520 uint humongous_regions_reclaimed() {
4521 return _humongous_regions_reclaimed;
4522 }
4523
4524 size_t bytes_freed() const {
4525 return _freed_bytes;
4526 }
4527 };
4528
4529 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4530 assert_at_safepoint_on_vm_thread();
4531
4532 if (!G1EagerReclaimHumongousObjects ||
4533 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4534 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4535 return;
4536 }
4537
4538 double start_time = os::elapsedTime();
4539
4540 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4541
4542 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4543 heap_region_iterate(&cl);
4544
4545 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4546
4547 G1HRPrinter* hrp = hr_printer();
4548 if (hrp->is_active()) {
4549 FreeRegionListIterator iter(&local_cleanup_list);
4550 while (iter.more_available()) {
4551 HeapRegion* hr = iter.get_next();
4552 hrp->cleanup(hr);
4553 }
4554 }
4555
4556 prepend_to_freelist(&local_cleanup_list);
4557 decrement_summary_bytes(cl.bytes_freed());
4558
4559 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4560 cl.humongous_objects_reclaimed());
4561 }
4562
4563 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4564 public:
4565 virtual bool do_heap_region(HeapRegion* r) {
4566 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4567 G1CollectedHeap::heap()->clear_in_cset(r);
4568 r->set_young_index_in_cset(-1);
4569 return false;
4570 }
4571 };
4572
4573 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4574 G1AbandonCollectionSetClosure cl;
4575 collection_set->iterate(&cl);
4576
4577 collection_set->clear();
4578 collection_set->stop_incremental_building();
4579 }
4580
4581 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4582 return _allocator->is_retained_old_region(hr);
4583 }
4584
4585 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4586 _eden.add(hr);
4587 _g1_policy->set_region_eden(hr);
4588 }
4589
4590 #ifdef ASSERT
4591
4592 class NoYoungRegionsClosure: public HeapRegionClosure {
4593 private:
4594 bool _success;
4595 public:
4596 NoYoungRegionsClosure() : _success(true) { }
4597 bool do_heap_region(HeapRegion* r) {
4598 if (r->is_young()) {
4599 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4600 p2i(r->bottom()), p2i(r->end()));
4601 _success = false;
4602 }
4603 return false;
4604 }
4605 bool success() { return _success; }
4606 };
4607
4608 bool G1CollectedHeap::check_young_list_empty() {
4609 bool ret = (young_regions_count() == 0);
4610
4611 NoYoungRegionsClosure closure;
4612 heap_region_iterate(&closure);
4613 ret = ret && closure.success();
4614
4615 return ret;
4616 }
4617
4618 #endif // ASSERT
4619
4620 class TearDownRegionSetsClosure : public HeapRegionClosure {
4621 private:
4622 HeapRegionSet *_old_set;
4623
4624 public:
4625 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4626
4627 bool do_heap_region(HeapRegion* r) {
4628 if (r->is_old()) {
4629 _old_set->remove(r);
4630 } else if(r->is_young()) {
4631 r->uninstall_surv_rate_group();
4632 } else {
4633 // We ignore free regions, we'll empty the free list afterwards.
4634 // We ignore humongous regions, we're not tearing down the
4635 // humongous regions set.
4636 assert(r->is_free() || r->is_humongous(),
4637 "it cannot be another type");
4638 }
4639 return false;
4640 }
4641
4642 ~TearDownRegionSetsClosure() {
4643 assert(_old_set->is_empty(), "post-condition");
4644 }
4645 };
4646
4647 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4648 assert_at_safepoint_on_vm_thread();
4649
4650 if (!free_list_only) {
4651 TearDownRegionSetsClosure cl(&_old_set);
4652 heap_region_iterate(&cl);
4653
4654 // Note that emptying the _young_list is postponed and instead done as
4655 // the first step when rebuilding the regions sets again. The reason for
4656 // this is that during a full GC string deduplication needs to know if
4657 // a collected region was young or old when the full GC was initiated.
4658 }
4659 _hrm.remove_all_free_regions();
4660 }
4661
4662 void G1CollectedHeap::increase_used(size_t bytes) {
4663 _summary_bytes_used += bytes;
4664 }
4665
4666 void G1CollectedHeap::decrease_used(size_t bytes) {
4667 assert(_summary_bytes_used >= bytes,
4668 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4669 _summary_bytes_used, bytes);
4670 _summary_bytes_used -= bytes;
4671 }
4672
4673 void G1CollectedHeap::set_used(size_t bytes) {
4674 _summary_bytes_used = bytes;
4675 }
4676
4677 class RebuildRegionSetsClosure : public HeapRegionClosure {
4678 private:
4679 bool _free_list_only;
4680 HeapRegionSet* _old_set;
4681 HeapRegionManager* _hrm;
4682 size_t _total_used;
4683
4684 public:
4685 RebuildRegionSetsClosure(bool free_list_only,
4686 HeapRegionSet* old_set, HeapRegionManager* hrm) :
4687 _free_list_only(free_list_only),
4688 _old_set(old_set), _hrm(hrm), _total_used(0) {
4689 assert(_hrm->num_free_regions() == 0, "pre-condition");
4690 if (!free_list_only) {
4691 assert(_old_set->is_empty(), "pre-condition");
4692 }
4693 }
4694
4695 bool do_heap_region(HeapRegion* r) {
4696 // After full GC, no region should have a remembered set.
4697 r->rem_set()->clear(true);
4698 if (r->is_empty()) {
4699 // Add free regions to the free list
4700 r->set_free();
4701 _hrm->insert_into_free_list(r);
4702 } else if (!_free_list_only) {
4703
4704 if (r->is_humongous()) {
4705 // We ignore humongous regions. We left the humongous set unchanged.
4706 } else {
4707 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4708 // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
4709 r->move_to_old();
4710 _old_set->add(r);
4711 }
4712 _total_used += r->used();
4713 }
4714
4715 return false;
4716 }
4717
4718 size_t total_used() {
4719 return _total_used;
4720 }
4721 };
4722
4723 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4724 assert_at_safepoint_on_vm_thread();
4725
4726 if (!free_list_only) {
4727 _eden.clear();
4728 _survivor.clear();
4729 }
4730
4731 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
4732 heap_region_iterate(&cl);
4733
4734 if (!free_list_only) {
4735 set_used(cl.total_used());
4736 if (_archive_allocator != NULL) {
4737 _archive_allocator->clear_used();
4738 }
4739 }
4740 assert(used_unlocked() == recalculate_used(),
4741 "inconsistent used_unlocked(), "
4742 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4743 used_unlocked(), recalculate_used());
4744 }
4745
4746 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4747 HeapRegion* hr = heap_region_containing(p);
4748 return hr->is_in(p);
4749 }
4750
4751 // Methods for the mutator alloc region
4752
4753 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4754 bool force) {
4755 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4756 bool should_allocate = g1_policy()->should_allocate_mutator_region();
4757 if (force || should_allocate) {
4758 HeapRegion* new_alloc_region = new_region(word_size,
4759 false /* is_old */,
4760 false /* do_expand */);
4761 if (new_alloc_region != NULL) {
4762 set_region_short_lived_locked(new_alloc_region);
4763 _hr_printer.alloc(new_alloc_region, !should_allocate);
4764 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4765 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4766 return new_alloc_region;
4767 }
4768 }
4769 return NULL;
4770 }
4771
4772 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4773 size_t allocated_bytes) {
4774 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4775 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4776
4777 collection_set()->add_eden_region(alloc_region);
4778 increase_used(allocated_bytes);
4779 _hr_printer.retire(alloc_region);
4780 // We update the eden sizes here, when the region is retired,
4781 // instead of when it's allocated, since this is the point that its
4782 // used space has been recored in _summary_bytes_used.
4783 g1mm()->update_eden_size();
4784 }
4785
4786 // Methods for the GC alloc regions
4787
4788 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4789 if (dest.is_old()) {
4790 return true;
4791 } else {
4792 return survivor_regions_count() < g1_policy()->max_survivor_regions();
4793 }
4794 }
4795
4796 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4797 assert(FreeList_lock->owned_by_self(), "pre-condition");
4798
4799 if (!has_more_regions(dest)) {
4800 return NULL;
4801 }
4802
4803 const bool is_survivor = dest.is_young();
4804
4805 HeapRegion* new_alloc_region = new_region(word_size,
4806 !is_survivor,
4807 true /* do_expand */);
4808 if (new_alloc_region != NULL) {
4809 if (is_survivor) {
4810 new_alloc_region->set_survivor();
4811 _survivor.add(new_alloc_region);
4812 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4813 } else {
4814 new_alloc_region->set_old();
4815 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4816 }
4817 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4818 _hr_printer.alloc(new_alloc_region);
4819 bool during_im = collector_state()->in_initial_mark_gc();
4820 new_alloc_region->note_start_of_copying(during_im);
4821 return new_alloc_region;
4822 }
4823 return NULL;
4824 }
4825
4826 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4827 size_t allocated_bytes,
4828 InCSetState dest) {
4829 bool during_im = collector_state()->in_initial_mark_gc();
4830 alloc_region->note_end_of_copying(during_im);
4831 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
4832 if (dest.is_old()) {
4833 _old_set.add(alloc_region);
4834 }
4835 _hr_printer.retire(alloc_region);
4836 }
4837
4838 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4839 bool expanded = false;
4840 uint index = _hrm.find_highest_free(&expanded);
4841
4842 if (index != G1_NO_HRM_INDEX) {
4843 if (expanded) {
4844 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4845 HeapRegion::GrainWords * HeapWordSize);
4846 }
4847 _hrm.allocate_free_regions_starting_at(index, 1);
4848 return region_at(index);
4849 }
4850 return NULL;
4851 }
4852
4853 // Optimized nmethod scanning
4854
4855 class RegisterNMethodOopClosure: public OopClosure {
4856 G1CollectedHeap* _g1h;
4857 nmethod* _nm;
4858
4859 template <class T> void do_oop_work(T* p) {
4860 T heap_oop = RawAccess<>::oop_load(p);
4861 if (!CompressedOops::is_null(heap_oop)) {
4862 oop obj = CompressedOops::decode_not_null(heap_oop);
4863 HeapRegion* hr = _g1h->heap_region_containing(obj);
4864 assert(!hr->is_continues_humongous(),
4865 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4866 " starting at " HR_FORMAT,
4867 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4868
4869 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4870 hr->add_strong_code_root_locked(_nm);
4871 }
4872 }
4873
4874 public:
4875 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4876 _g1h(g1h), _nm(nm) {}
4877
4878 void do_oop(oop* p) { do_oop_work(p); }
4879 void do_oop(narrowOop* p) { do_oop_work(p); }
4880 };
4881
4882 class UnregisterNMethodOopClosure: public OopClosure {
4883 G1CollectedHeap* _g1h;
4884 nmethod* _nm;
4885
4886 template <class T> void do_oop_work(T* p) {
4887 T heap_oop = RawAccess<>::oop_load(p);
4888 if (!CompressedOops::is_null(heap_oop)) {
4889 oop obj = CompressedOops::decode_not_null(heap_oop);
4890 HeapRegion* hr = _g1h->heap_region_containing(obj);
4891 assert(!hr->is_continues_humongous(),
4892 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4893 " starting at " HR_FORMAT,
4894 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4895
4896 hr->remove_strong_code_root(_nm);
4897 }
4898 }
4899
4900 public:
4901 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4902 _g1h(g1h), _nm(nm) {}
4903
4904 void do_oop(oop* p) { do_oop_work(p); }
4905 void do_oop(narrowOop* p) { do_oop_work(p); }
4906 };
4907
4908 // Returns true if the reference points to an object that
4909 // can move in an incremental collection.
4910 bool G1CollectedHeap::is_scavengable(oop obj) {
4911 HeapRegion* hr = heap_region_containing(obj);
4912 return !hr->is_pinned();
4913 }
4914
4915 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4916 guarantee(nm != NULL, "sanity");
4917 RegisterNMethodOopClosure reg_cl(this, nm);
4918 nm->oops_do(®_cl);
4919 }
4920
4921 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4922 guarantee(nm != NULL, "sanity");
4923 UnregisterNMethodOopClosure reg_cl(this, nm);
4924 nm->oops_do(®_cl, true);
4925 }
4926
4927 void G1CollectedHeap::purge_code_root_memory() {
4928 double purge_start = os::elapsedTime();
4929 G1CodeRootSet::purge();
4930 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4931 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4932 }
4933
4934 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4935 G1CollectedHeap* _g1h;
4936
4937 public:
4938 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4939 _g1h(g1h) {}
4940
4941 void do_code_blob(CodeBlob* cb) {
4942 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4943 if (nm == NULL) {
4944 return;
4945 }
4946
4947 if (ScavengeRootsInCode) {
4948 _g1h->register_nmethod(nm);
4949 }
4950 }
4951 };
4952
4953 void G1CollectedHeap::rebuild_strong_code_roots() {
4954 RebuildStrongCodeRootClosure blob_cl(this);
4955 CodeCache::blobs_do(&blob_cl);
4956 }
4957
4958 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4959 GrowableArray<GCMemoryManager*> memory_managers(2);
4960 memory_managers.append(&_memory_manager);
4961 memory_managers.append(&_full_gc_memory_manager);
4962 return memory_managers;
4963 }
4964
4965 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4966 GrowableArray<MemoryPool*> memory_pools(3);
4967 memory_pools.append(_eden_pool);
4968 memory_pools.append(_survivor_pool);
4969 memory_pools.append(_old_pool);
4970 return memory_pools;
4971 }